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.TH SMAIL X_MAN5_EXT_X "1 February 1988" "Local"
.SH NAME
X_LIB_DIR_X/* \- configuration files used by smail
.SH SYNOPSIS
.B "X_LIB_DIR_X/config"

.B "X_LIB_DIR_X/directors"

.B "X_LIB_DIR_X/routers"

.B "X_LIB_DIR_X/transports"

.B "X_LIB_DIR_X/qualify"

.B "X_LIB_DIR_X/methods/"
.SH DESCRIPTION
The
.IR config ,
.IR directors ,
.IR routers ,
.IR transports ,
and
.I qualify
files describe the rules used by
.IR smail (X_MAN8_EXT_X)
in processing and delivering mail.
In addition to these configuration files,
.I method
files may be pointed to by entries in the
.I routers
file.
The actual paths may differ from system to system
and, in addition, the paths to these files,
with the exception of the config file itself,
may be changed in the config file.
.PP
.I Smail
is compiled with a default configuration.
This default configuration is suitable for many sites that
communicate to other systems via UUCP, or SMTP.
For such sites, no configuration files are needed,
though it may still be convenient to have a
.I config
file for attributes (described below) such as
.B smart_user
and
.BR smart_path .
See the section
.B "DEFAULT CONFIGURATION"
for more details.
.SH "COMMON FORMAT CONVENTIONS"
In all files used by
.IR smail ,
entries begin with a character in column 1
that is not white space or the character `#'.
Entries continue until the next line
which begins with a character other than white-space
or the character `#',
or until the end of the file is encountered.
.PP
Comments begin with the character `#',
in any column and end at the next newline.
A `#' in the first column, does not signify the
end of an entry.
.PP
Variable and attribute names in configuration files
are formed of characters from the
set of letters, numbers and the
character `_'.
.PP
String values may be enclosed in double
quotes,
in which case backslash escapes are
processed as in C.
If string values are not enclosed
in double quotes,
the values are limited to characters
from the set of letters, digits and
the characters
.B "! @ $ % ^ & * \- _ + ~ / ? | < > : [ ] { } . '
and
.BR "`" .
.PP
Numbers are as in C,
with a prefix of 0 specifying an octal
constant
and a prefix of 0x specifying a
hexadecimal constant.
In addition,
a suffix of
.I k
or
.I K
specifies a multiplier of 1024
and a suffix of
.I m
or
.I M
specifies a multipler of 1048576, or 1024K.
.SH "String Expansion"
Some string values will be variable and filename expanded before being used.
When this is done, certain substrings, beginning with $, will
be replaced by the value of a
.I smail
variable.
The names of expansion variables are either a single
character, or are multiple characters from the set of letters,
digits and underscore.  A variable name can also be
enclosed between { and }, to isolate the variable name from
the surrounding text.
.PP
In addition to variables, a number of meta-expansions can be
used.  These expansions are always of the form:

.RS
${\fImeta_name\fP:\fIname\fP}
.RE

where
.I meta_name
defines some operation to perform on the
value of the variable
.IR name .
Multiple meta-expansions can be
specified, and they are processed from right to left.  For example:

.RS
${lc:strip:user}
.RE

This strips quotes from the value of the variable
.B user
and
then converts characters to lower case.
.PP
When a string to be expanded begins with the character `~', a
home directory is substituted.  If only `~' is given, or `~/'
is given, then the home directory associated with an address
is substituted.  If the form ``~\fIusername\fP'' is given, where
.I username
is the name of a user on the local host, that
user's home directory is substituted.
.PP
The complete set of variable names depends upon context, but
the following are always available:
.TP .8i
.B bat
a string defining a string of characters which identifies where
your smail sources originated.  See the source file
.I src/version.c
for more information.
.TP .8i
\fBcompile_date\fP or \fBld_date\fP
the date when the current smail binary was compiled.
.TP .8i
\fBcompile_num\fP or \fBld_num\fP
a decimal number giving the number of times smail has
been compiled since the creation of the source file
.IR ldinfo.c .
.TP .8i
.B ctime
the date and time, in the form returned by the
.IR ctime (3)
function.
.TP .8i
.B date
The date and time in ARPAnet format.
.TP .8i
.B spool_date
The date and time that the message was received by the local host, in
ARPAnet format.
.TP .8i
.B grade
The priority character for the
current message.
See the
.B grades
attribute in the
.I config
file for more information
on this value.
.TP .8i
\fBmessage_id\fP or \fBid\fP
the message ID for the current message.
.TP .8i
\fBpatch_number\fP or \fBpatch\fP
the patch level of the smail sources,
from the source file
.IR patchnum ,
which contains the date that the most recently applied patch was
created, and the number of that patch.
.TP .8i
.B patch_date
The date when the most recently applied patch was created.
.TP .8i
\fBpid\fP or \fB$\fP
the current process ID.
.TP .8i
\fBprimary_name\fP or \fBprimary\fP
the canonical name for the local host.
.TP .8i
\fBrelease_date\fP or \fBrelease\fP
the release date of the smail sources.
.TP .8i
.B sender
\fBsender\fP or \fBfrom\fP
the address of the sender of a message.
.TP .8i
.B uucp_name
the UUCP-network name for the local host.
.TP .8i
.B version
a short version string for
.IR smail .
.TP .8i
.B version_string
a verbose version string for
.TP .8i
\fBvisible_name\fP or \fBname\fP
the local host name used in outgoing addresses.
.TP .8i
\fBsmail_lib_dir\fP or \fBlib_dir\fP
the value of the config file variable
.BR smail_lib_dir ,
which is the directory in which configuration files are found.
.PP
In addition, the following variables are defined if
they are available in the current context:
.TP .8i
\fBHOME\fP or \fBhome\fP
the home directory of a user associated with an address.
.TP .8i
.B host
the remote host string associated with a remote address.
.TP .8i
\fBuser\fP or \fBaddr\fP
a user name or remaining address string associated with
an address.
.PP
These variables may exist if such data is available:
.TP .8i
.B inet_name
the internet address for the local host,
in decimal bytes separated by
a dots.  For example: ``192.2.12.3.''
.TP .8i
.B hex_inet_name
the internet address in hexadecimal.
For example:  ``c0020c03.''
.PP
The following meta-expansions also exist:
.TP .8i
.B lc
convert to lower case.
.TP .8i
.B parent
interpret the value
within the context of the parent
local address that produced the associated address.
This is useful when the local
address that produced an address is
desired.
Expansion fails if no parent exists.
.TP .8i
.B quote
enclose the value in quotes, if it
would not otherwise be a valid
local-form address,
within the rules of RFC822.
Uses backslash escapes as appropriate.
(This is not available in the Alpha release of
smail).
.TP .8i
.B strip
Remove backslashes and double quotes
from a value.  If a double-quote is
preceded by a backslash, the
backslash is removed, but the double
quote is not.  Sequences of
whitespace characters and dots are
converted to exactly one dot
character.
.TP .8i
.B top
interpret the value
within the context of the original address,
supplied to the mailer, that produced the
associated address.
.TP .8i
.B uc
convert to upper case.
.PP
The following are sample expansions:

.nf
	/usr/spool/mail/${lc:user}
.fi

with a
.B $user
value of ``Tron'' will become:

.nf
	/usr/spool/mail/tron
.fi

whereas:

.nf
    	Received: by $primary_name ($version_string)
		id <$message_id@primary_name>;
		$spool_date
.fi

will become something such as:

.nf
    	Received: by futatsu.uts.amdahl.com (smail 3.0.2 03-dec-87)
		id <m0c87zK-007zXpC@futatsu.uts.amdahl.com>;
		Tue,  8 Dec 87 19:45 PST
.fi

and:

.nf
    	$host!rmail ${strip:addr}
.fi

with an
.B $addr
value of ``Ronald S. Karr'' and a
.B $host
value of ``amdahl'' will become:

.nf
    	amdahl!rmail Ronald.S.Karr
.fi

If a value does not exist
(such as
.B $HOME
being used when no
associated home directory is known,
or when a string begins
with "~\fIusername\fP" and the
.I username
is not known,
or when
.B $host
is used for a local address)
then the expansion fails.
.SH "THE CONFIG FILE"
The config file defines values for global variables used by
.IR smail .
Each entry in this file gives the
name of a variable to be set and defines a string, numeric
or boolean value to give to that variable.
The recognized forms for entries in the config file are:

.RS
\fBvariable_name\fP = \fIstring\fP or \fInumber\fP

\fBvariable_name\fP  or  +\fBvariable_name\fP

\-\fBvariable_name\fP
.RE

The first form above sets the variable to a string or numeric value,
the second form sets a boolean variable,
and the last form resets a boolean variable, clears a string value
or sets a numeric value to zero.
.PP
The following config file specifies a spool file
mode of 0400,
a maximum message size of 200K,
a method directory of
.I /usr/lib/smail/method
and disables use of a transport configuration:

.RS
.nf
# don't allow others to read spool files
spool_mode = 0400

# truncate messages that are too large
max_message_size = 200k

# method files are stored in this directory
method_dir = /usr/lib/smail/method

# we are using the built in transport definitions,
# so don't bother looking for a transport file
\-transport_file
.fi
.RE

The complete list of recognized attributes is given
in the following table,
in alphabetic order.
Note that the default values can be changed when
compiling the
.I smail
program.
.br
.DD auto_mkdir boolean on
If set, then any directories required for spooling and logging
will be created if they do not exist.
Smail will never try to create required parent directories.
.DD auto_mkdir_mode integer 0755
When directories are created automatically by smail,
they are created with this permission mode mask.
See
.IR stat (2)
for information on what this mode represents.
.DD console string /dev/console
The file name for the console device.  This filename
is used as a last resort in attempting to write panic
messages.
.DD copying_file string "``COPYING''"
The pathname to the
.I COPYING
file, which describes your
distribution rights and details the warranty information
from the authors of smail.  If this does not begin with ``/'', it will
be referenced relative to the
.I smail_lib_dir
directory.
.DD date_field string "``Date: $date''"
This string will be expanded to form the
.B Date:
header field.
This will be used if such a field does
not already exist in the header.
.DD delivery_mode string "``foreground''"
The default mode of delivery for new mail.
This can be one of the values
``foreground''
(immediate delivery in the process that received the message),
``background''
(immediate delivery in a child process,
where the process that received the message exits immediately),
or
``queued''
(do not attempt delivery until a later queue run).
.DD director_file string "``directors''"
Names the file containing the director configuration
information.  If this does not begin with ``/'', it will be referenced
relative to the
.I smail_lib_dir
directory.
.DD fnlock_interval number 3
The sleep interval between retries while attempting to
lock mailbox files with a lockfile-based locking
protocol.  On systems where sleep has a 1 second granularity, this
value should be at least 2.
.DD fnlock_mode number 0666
Mailbox lock files are created with this mode.
.DD fnlock_retries number "0 if you have an atomic rename, 5 otherwise"
The number of times to attempt to lock mailbox files using
a file-based locking protocol.
.DD grades string "special-delivery:9:air-mail:A:first-class:C:bulk:a:junk:n"
The priority, or grade, characters corresponding to particular values
of the
.B Precedence:
field in the message header.  The parts of the
string are separated by `:' with alternating precedence string and
grade character.
Numbers are higher in priority than upper case letters which
are in turn higher than lower case letters.
Also, lower numbers are higher in priority than higher numbers,
and the same goes for letters lower in the alphabet.
Grades in
the range
.B [a\-m]
will only have an error message and header returned
to the sender on errors,
rather than including the message body as well.
Grades in the range
.B [n\-z]
will not have anything returned to the sender on errors.
.sp .4v
The precedence names recognized by many BSD sendmail configurations are:
.IR special-delivery ,
.I first-class
and
.IR junk .
Others are useful mainly for getting mail out
of the local machine or for communication with other machines
running
.I smail
in a similar configuration.
The grade character for a message is available in string expansions
as the
.B $grade
variable.
.DD hit_table_len number "241 with a large address space, 13 otherwise"
The length of an internal address hit table.
Addresses are hashed into this table to prevent multiple deliveries
to the same address.
Longer tables speed address hashing
at a small memory expense.
.sp .4v
NOTE: this value may be ignored in the future.
.DD "hostnames \fRor\fP hostname" string "computed at run time"
A colon-separated list of names for the local host.
This list, together with
.I uucp_host
and
.I more_hostnames
should
represent all possible names for the local host.  Note that the
.I visible_name
hostname is not recognized as a name for the local host unless it also
appears in the value for one of the other hostname variables.
For a host that is in more than one domain
or that can gateway to more than one level of domains,
this should represent those names.
For a host in a registered domain in the UUCP zone,
which is also in the maps distributed over
USENET,
\fIlocalhost\fP\fB.uucp\fP
should also be in the list.
The first value in
.I hostnames
is used internally as a special
``primary name''
for the local host.

If
.I hostnames
is set turned off
(which is generally the default)
then the hostnames value will be computed by
pairing the localhosts's name, computed in a system-dependent
manner, with all values in the
.I visible_domains
attribute list.
.DD lock_by_name boolean system-dependent
If this is on, then
input spool file locking is always based on lock files.
Otherwise,
an inode-based locking mechanism may be used,
such as
.I flock(2)
under BSD, or
.I lockf(3)
under System V.
Inode-based locking is more efficient,
if available.
However,
lock files can be easily created by shell scripts which
may be advantageous under some circumstances.
.DD lock_mode number 0444
The creation mode for lock files.
.DD log_mode number 0664
The creation mode for the various mail system
log files.
.DD logfile string "``X_LOGFILE_X''"
The name of a file to which
transaction and error messages are appended.
If this file does not exist,
it is created with a mode from the
.I log_mode
attribute.
.DD max_hop_count number 20
If the hop count for a message equals or
exceeds this number,
then attempts at remote delivery will
result in an error message being returned to
the sender.
This is used to prevent infinite loops.
The hop count for a message can be set using the
.B \-h
option when invoking
.IR smail .
Otherwise it is computed from the number
of
.B Received:
fields in the message header.
.DD max_load_ave number 0
For systems on which a load average can be computed,
this specifies the maximum load average at
which mail delivery will be performed, otherwise
this value is ignored.
If the load average exceeds this number,
incoming mail will be saved in the input
spool directory,
though no delivery will be performed.
If this value is 0 the load average will not be
computed and delivery will always be performed.
Normally the load average refers to a 5 minute
load average.
(This is not currently implemented)
.DD max_message_size number 100k
Messages longer than this will
be truncated by
.I smail
when when written to its input queue.
(This is not currently implemented and there
is no limit on the size of messages).
.DD message_buf_size number "100k with a large address space, BUFSIZ otherwise"
The size of an internal buffer
for reading and writing messages.
For systems with a reasonable VM space,
this can be equal to the maximum size for
messages.
Specifying the value of 
in which case reading messages and then
delivering them to one or more destinations requires very
few read calls,
as the entire message is always kept in memory.
BUFSIZ, here, refers to the defined symbol in /usr/include/stdio.h.
.DD message_id_field string "``Message-Id: <$message_id@$primary_name>''"
This string will be expanded to form the
.B Message-Id:
header field.
This will be used if such a field does
not already exist in the header.
.DD message_log_mode number 0644
Each message has associated with it a unique
file containing a transaction log for that
message.
This number specifies the creation mode for
this log file.
.DD method_dir string "``methods''"
If a
.B method
attribute for a router does not specify
a pathname beginning with `/',
then this directory is prepended to the path
to form the complete path for the method file.  If this does not begin
with ``/'', it will be referenced relative to the
.I smail_lib_dir
directory.
See the description of the router file for
more information on method files.
.DD more_hostnames string off
A colon-separated list of hostnames.
This list is in addition to any names which may have been
computed from the
.B visible_domains
attribute in forming the value of
.BR hostnames .
Thus,
it is useful for specifying names which are not formed
from the computed name for the host.
.DD nobody string "site-dependent: often ``nobody''"
This names a default user that defines
permissions when no other user is specified.
Also, this user is used
in some conditions when it is not certain
whether a set of actions can be trusted,
if performed under other, potentially
more powerful users.
This should reference a login id
which has few or no capabilities for doing
harm or accessing protected files.
.DD paniclog string "``X_PANICLOG_X''"
The name of a file to which
panic and very important error messages are appended.
If this file does not exist,
it is created with a mode from the
.I log_mode
attribute.
Entries written to this log file represent
problems that require human intervention,
such as configuration errors or
directory permission errors preventing
mail spooling or delivery.

Configuration errors generally cause
mail to be moved into a special
.I error/
directory under the
input spool directory,
thus preventing attempts at redelivery until
the configuration error has been corrected.

Thus, both the panic log and the
.I error/
directory should be checked periodically
under normal use,
and frequently after configuration changes.
When any problems have been resolved,
these messages can be requeued for delivery
by using
.IR mv (1)
to move the spool files back to the
spool directory.
.DD "postmaster_address \fRor\fP postmaster" string ``root''
This is the default address for the postmaster.  If the address
.I Postmaster
is not resolved by any of the configured directors, then this address
is used.
.DD qualify_file string "``qualify''"
Names the file containing the hostname qualification information.
If this does not begin with ``/'', it will be referenced
relative to the
.I smail_lib_dir
directory.
.DD queue_only boolean off
If this is set then
.I smail
will not immediately
attempt delivery for incoming mail.
The
.I smail
program will then only attempt delivery when
explicitly processing the input queue,
such as when invoked with the
.B \-q
flag.
.BD received_field string
This string will be expanded to form the
.B Received:
header field.
This field will be inserted into the header
if the
.B received
attribute is not explicitly turned off
for a transport.
The default value for
.B received_field
is:

.nf
	Received: by $primary_name ($version_string)
		id <$message_id@$primary_name>; $spool_date
.fi

.DD require_configs boolean off
If this is not set, then configuration files are not required to exist.
This applies to the primary and secondary config files and
the director, router and transport files.
If one of these files does not exist then it is ignored and
internally compiled configuration is used instead.
If this attribute is set, then any configuration file, which does
not have a NULL filename (for example, using
.B \-router_file
to set the name for the router file to NULL)
and which does not exist,
will generate a panic message from the mailer.
.DD return_path_field string "``Return-Path: <$sender>''"
This string will be expanded to form the
.B Return-Path:
header field.
This field will be inserted into the header
if the
.B return_path
attribute is turned on for a transport.
.DD router_file string "``routers''"
Names the file containing the router configuration
information.  If this does not begin with `/', it will be referenced
relative to the
.I smail_lib_dir
directory.
.DD second_config_file string none
This names a secondary configuration file which can
define attribute values which override internal
defaults and values in the primary configuration
file.  If this does not begin with ``/'', it will be referenced
relative to the
.I smail_lib_dir
directory.
This is primarily useful in networks containing machines
that share filesystems.
By having a shared primary configuration file
most systems on a network need not be concerned with
maintaining the
.I smail
program,
while other systems may want or need to use a
different configuration,
while sharing the same binary.
In particular, the
.BR smart_user ,
.B smart_path
and
.B smart_transport
attributes are common attributes to be set in
the secondary configuration file.
.DD smail string "``X_SMAIL_NAME_X"
Name a valid path to a
.I smail
binary that can be used to
re-exec
.I smail
when a major configuration change has
been detected,
or to exec
.I smail
when delivering error messages.  If this does not begin with ``/'', it
will be referenced relative to the
.I smail_lib_dir
directory.
.DD smail_lib_dir string "``X_LIB_DIR_X''"
This defines the path to the smail configuration file directory.  The
router, director and transport files, as well as alias and path
files and method files may be referenced relative to this directory.
.DD smart_path string none
This defines the default value for the
.B path
attribute used by the
.I smarthost
router driver.
This gives the path to a machine
which supposedly contains a more
complete routing database than is available
on the local host.
See a later section describing the
smarthost driver for more information on the use
of this attribute.
.DD smart_transport string none
This defines the default value for the
.B transport
generic attribute used by the
.I smarthost
router driver.
See a later section describing the
smarthost driver for more information on the use
of this attribute.
.DD smart_user string none
This defines the default value for the
.B smart_user
attribute used by the
.I smartuser
director driver.
.BD smtp_banner string
This string will be expanded to form the SMTP startup banner that is
written by the SMTP server when a connection request is accepted.
Each line of this message is automatically preceded by a 220
identification code, and newlines are correctly changed into a
carriage-return newline sequence.  The default value for
.B smtp_banner
is:

.nf
	$primary_name Smail$version #$compile_num ready at $date
.fi


.DD smtp_debug boolean on
This boolean variable controls the meaning of the DEBUG command when
receiving SMTP commands.  If the variable is on, then the DEBUG command
(with an optional debugging level) sets debugging to the specified
level, or 1 if no level was specified.  The debugging output will
be written over the SMTP connection.
.DD spool_dirs string "``X_MAIN_SPOOL_DIR_X''"
This defines one or more directories into which
incoming mail can be spooled.
Directories are separated by single colon
characters.
When writing a message to the first spool directory
fails,
(say due to permission problems, filesystem full errors, etc.)
successive spool directories are tried until
the incoming message can be successfully written
or until no more alternative directories exist.
Each spool directory is expected to have writable subdirectories of:
.I input
(to hold the actual spool files),
.I lock
(for temporary lock files),
.I msglog
(for temporary per-message transaction logs and audit trails)
and
.I error
(to hold messages which failed due to configuration errors or other
problems which require human intervention).
.DD spool_grade character "``C''"
This character names the default grade for messages.
This can be overridden by a
.B Precedence:
field in the message header.
The grade is used in sorting messages in the
input spool directory
and is also available in string expansions
as the
.B $grade
variable.
See the
.B grades
attribute for more information.
.DD spool_mode number 0440
This defines the file creation mode for spool files.
.DD transport_file string "``transports''"
names the file containing the transport configuration
information.  If this does not begin with ``/'', it will be referenced
relative to the
.I smail_lib_dir
directory.
.DD trusted_users string "``root:uucp:daemon''"
This names a list of users (separated by colons) who are trusted to
specify a sender for a message.
Users who are not in this list cannot specify a
.B Sender:
header field without it being removed.
If such users specify a
.B From:
header field, then a
.B Sender:
field will be created that specifies the real
user that submitted this mail.
Generally,
this should be set to that names of all users under
which remote mail is received and sent to
.IR smail .
If this list is turned off,
using the form
.BR \-trusted ,
then all users are trusted.

.B NOTE:
The real user ID is used in verifying
trusted users.  However, under many operating systems,
the /usr/lib/uucp/uucico program runs under the real uid
of the user that ran
.I /usr/lib/uucp/uucico.
Often any user can run the
.I uucico
program.
The
.I smail
program cannot differentiate this case from any other case
and will thus do the ``wrong thing'' here.
If this problem exists on your machine,
then the trusted attribute may need to be turned off.
This problem is particularly difficult to resolve on
System V machines where non-superuser programs
are unable to change their real uid.
.DD trusted_groups string off
This names a list of groups (separated by colons) that are trusted
to specify a sender for a message.  The groups specified are checked
against the effective gid of smail.  Thus, if smail is a setgid program,
then this string is of no value and should be turned off.  However,
if smail is not set gid, then programs that invoke smail under a specific
effective gid, while not a specific real uid, can be detected and can
be properly treated as trusted.
.DD uucp_name string "computed at run time"
This specifies a name for the local host.
This name is available in string expansions as the
.B $uucp_name
variable.
It is also used in the
``remote from \fIhostname\fP''
suffix to
``From\fI<space>\fP''
lines for mail being delivered to remote
machines, when the
.B from
attribute is turned on for a transport.
.DD visible_domains string "uucp"
.PD 0
.DD visible_name string "computed at run time"
.PD
The full domain name used in outgoing mail addresses within
header fields.
If
.B visible_name
is turned off,
then it will be set to the first name
from the
.B hostnames
attribute.
If the
.B hostnames
attribute is not specified
then that attribute will be filled in
with hostnames of the form \fIhostname\fP.\fIvisible_domain\fP,
where
.I hostname
is derived in a system-dependent manner
and where
.IR visible_domain ,
here,
is one name from the
.B visible_domains
list attribute.
Each entry in the
.B visible_domains
list is used, in order, to created the
.B hostnames
value.

For sites in the UUCP zone
.B visible_domains
will often merely be the string ``uucp''.
Finally,
the variable
.B $visible_name
is available in string expansions.
.br
.SH DIRECTOR, ROUTER AND TRANSPORT FILE FORMATS
The
.IR director ,
.IR router
and
.I transport
configuration
files share a common format,
which is described in this section.
The specific contents for each file are described in later sections.
.PP
Each entry in one of these files specifies a name for
the entry, a set of
.I generic
attributes and a set of
.I driver
attributes.
The generic attributes and the driver attributes
define the characteristics for the entry.
.PP
The list of possible generic attributes
are common to all entries in a configuration file.
One generic attribute is always required:
the
.B driver
attribute.
This attribute names the underlying
set of functions that will
be used when using that entry.
The list of possible driver attributes are specific to
different types of drivers.
.PP
The form of an entry is:

.nf
	\fIentry_name\fP:
		\fIgeneric_attribute\fP , ... ; \fIdriver_attribute\fP , ...
.fi

where a comma separates the definitions for specific attributes
and where a semicolon separates the generic attributes from
the driver attributes.
It is
.I not
an error for an entry to end in a comma or
semicolon.
The form for generic and driver attributes is the same as for
entries in the config file.
.PP
As an example, consider an entry in the transport file
that specifies use of the program /bin/mail to
deliver mail to local users.
The mail messages are to contain a ``Return-Path:''
header field,
and the /bin/mail program is to be given no
more than 20 addresses per invocation.
A simple entry to specify this is:

.nf
	# call /bin/mail to deliver to local users
	local: max_addrs=20, return_path, driver=pipe;
		cmd="/bin/mail $($user$)"
.fi

.SH "INTERACTION BETWEEN DIRECTORS, ROUTERS AND TRANSPORTS"
To better understand the use of the
.IR director ,
.I router
and
.I transport
files,
this section describes, briefly,
how address resolving
and delivery is accomplished in
.IR smail .
The configuration specified in these files
is intimately involved in this process.
.PP
When
.I smail
is given a list of addresses to which
a message is to be delivered,
the list is processed iteratively
until a list of resolved addresses is produced.
When an address is resolved,
the transport (the part of
.I smail
that
performs delivery of messages to local users
or remote hosts) and all data required by the transport
will be known.
.PP
To accomplish this the
.I smail
program
goes through the following
steps:
.IP a. 4n
Each address is parsed to find a hostname,
called the
.IR target ,
and the remaining part of the address,
called the
.IR remainder .
As a simple example, in the address
.IR "tron@uts.amdahl.com" ,
the host part
.I uts.amdahl.com
is the target and
.I tron
is the remainder.
In the address
.IR "sun!amdahl!tron" ,
the target is
.I sun
and the remainder is
.IR amdahl!tron .
More information on addresses can
be found in
.IR mailaddrs(X_MAN5_EXT_X) .
.IP b. 4n
Each local address
is given to directors, in the order specified by the director file,
until one of the directors
says that it knows what to do with that address.
That director has the option of
returning a new list of addresses
or of putting the address on a list
of resolved addresses.
If new addresses are produced,
they are put on the input list,
to be processed from step a.
.IP c. 4n
Each remote address is passed to routers,
in the order specified by the router file,
until one of the routers is able to match the
target name for the address.
If no router is able to match the complete target, then
the first router with the longest match will be used.
The router specifies the transport to be
used for delivery to that address,
plus some other information required by
the transport,
such as the
.I "next host"
and
.I "next address"
values.
The transport may come from a router default, a method file
of may be specified by the router specifically.
.PP
When all addresses have been resolved,
they are sorted out and passed to
transports.
It is the job of the transport
to deliver a message to the
set of addresses that it is given.
.PP
It is important to know that all hostnames and local usernames are
matched independent of case, so that, for example,
.IR Postmaster ,
.I POSTMASTER
and
.I postmaster
all compare equal.  In addition an internal hash table is kept of all
regular recipient addresses, that is, all addresses which do not
specify files or shell commands.  This table is used to discard
duplicate regular recipient addresses.  This hash table is independent
of case, as well, so that the address
.I Postmaster@SRI-NIC.ARPA
is considered a duplicate of
.IR postmaster@sri-nic.arpa .
.SH "THE DIRECTOR FILE"
The
.I director
file describes the operations,
and their order,
for handling local addresses.
For example,
some possibilities are to expand a local address
into a list of local and remote addresses
through an alias file, forward file or mailing list,
or to cause mail to be delivered to a local user.
.PP
The following list describes the possible
generic attributes for director file entries:
.BD caution boolean
If set then be cautious of addresses produced by this
director.  If the nobody attribute is not
set, then reject file, shell command
or
.IR :include:filename -style
mailing list addresses.
.BD default_group string
If the driver does not associate a group
to an address returned by it, then
associate the group id for this group
name.  This will override the gid set by a
.B default_user
attribute.
.BD default_home string
If the driver does not associate a home
directory with an address returned by it,
then use this home directory.
The value will be expanded to form the actual directory pathname.
At the present time, the
.B $user
variable is not available for
this expansion.
If the string expansion fails,
it is ignored.
.BD default_user string
If the driver does not associate a user
or group to an address returned by it,
then associate the user id and group id
of this user.
.BD driver string
The driver attribute names a specific set of low-level
functions which will do the work of directing
local mail.  This attribute is required.
.BD nobody boolean
If set, then access files, or run shell
commands as the user specified
by the
.B nobody
attribute,
for
addresses flagged with
.I caution
by either the
.B caution
generic attribute or by the driver.
Association of nobody with an address
overrides the default_user,
default_group, set_user and set_group
attributes.
This attribute is set by default.
.BD owner string
Names the address to be sent mail if an error
occurs in processing the addresses
produced by this director.
This string is expanded
with the variable
.B $user
set to the local-form
address passed to the director.
Commonly the value will be ``owner-$user''.
If this string expansion fails,
it is ignored.
.BD sender_okay boolean
If set, then it is always okay for this attribute to
produce an address equal to the sender.
This effectively turns on the
.I "me too"
flag for this director.
This should generally be set for
forwarding directors and should not be
set for aliasing and mailing list
directors.
.BD set_group string
Associate the gid for this group with the
addresses returned by the driver.  This
overrides any gid set by the
.B set_user
attribute.
.BD set_home string
Associate this home directory with all
addresses returned by the driver.  This
will be expanded in the same manner as
.BR default_home .
.BD set_user string
Associate the uid and gid for this user
with addresses returned by the driver.
This overrides any values set by the driver.
.PP
There are two addresses which are required by the mailer software to
exist: the address
.I Postmaster
and the address
.IR Mailer-Daemon .
To avoid the necessity of an alias for these two users, smail contains
two implicit directors embedded into the directing code.  These
implicit directors are used as a last resort.  The first such director
maps the address
.I Mailer-Daemon
onto the address
.I Postmaster
and the second maps
.I Postmaster
onto the address
.IR root .
.SH "THE ROUTER FILE"
The
.I router
file describes the operations,
and their order,
for handling remote addresses.
For example,
some possibilities are to lookup hostnames in a routing database,
to match a special domain-literal form,
or call a program to return a list of neighboring hosts.
.PP
The following list describes the possible
generic attributes for router file entries:
.BD always boolean
Routers will not always find a complete match for a particular
hostname.
For example,
if a routing database has a route to the domain
.I amdahl.com
but not to the hostname
.I futatsu.uts.amdahl.com
then the routing driver might return
the route to
.IR amdahl.com .
Generally,
the route for the longest match of the target host
is used.
However,
if the
.B always
attribute is set,
then any match found by this router
will be used in preference to routes that might have been returned by
routers
.IR "later in the router list" .
This is useful for hardwiring a certain number of
routes within a small database.
For example, this is useful for Internet sites that
gateway for a small number of UUCP sites
in the UUCP zone.
.BD driver string
The driver attribute names a specific set of low-level
functions which will do the work of routing
remote mail.  This attribute is required.
.BD method string
.PD 0
.BD transport string
.PD
The router driver has the option of specifically setting a transport
to use for remote delivery.
If the driver does not do so,
then either a
.B method
or a
.B transport
attribute must exist to specify how the mail is to be delivered.
A
.B method
attribute specifies a file which contains a table relating
hostnames to transports.
A
.B transport
attribute specifies a specific transport.
If the method file does not contain a match for all hosts,
then the transport named with the
.B transport
attribute is used.
The format of a method file is given in the next section.
.SH "METHOD FILES"
Method files define a relation between a set of hostnames
and a set of transports to be used in delivering to
those hostnames.
Method files use the standard routine for reading
file entries,
just as with the
.IR config ,
.IR director ,
.IR router
and
.I transport
files.
Each entry should have the form:

.nf
	\fIhostname\fP	\fItransport-name\fP
.fi

stating that mail being sent to
.I hostname
should be delivered using the transport
.IR transport-name .
As a special case,
if the
.I hostname
value is the special string ``*'',
the entry matches any host.
This is a catch-all feature which should
only be used in the last entry in a
method file.
.SH "THE TRANSPORT FILE"
The
.I transport
file describes the various possible ways,
of delivering mail.
For example,
some possibilities are to call a program such as
.IR uux (1)
to deliver mail to a remote host,
to connect over TCP/IP to a remote host
and converse using an SMTP protocol,
or to deliver local mail by appending to a user's
mailbox file.
.PP
The following list describes the possible
generic attributes for transport file entries:
.BD bsmtp boolean
Use a batched SMTP format,
where the message is enclosed in an envelope of SMTP
commands.
This is not the same format commonly used on BITNET,
as it does not contain FORTRAN carriage control
characters.
This can be used to send mail to remote hosts using
SMTP formats even when direct two-way connections are
not feasible.
For example, this will work over UUCP and eliminates
difficulties with sending arbitrary addresses
as arguments to UUX.
Use of
.B bsmtp
also turns on the
.B dots
attribute.
When used with the
.B uucp
attribute, UUCP-style !-path addresses are used in the SMTP envelope.
.BD crlf boolean
If set,
then each line of the header and message
will end in carriage-return/line-feed rather than
a single newline character.
This is not typically useful,
as the SMTP transport,
which requires this as a part of the interactive protocol
always does this anyway.
.BD debug boolean
If set,
replaces the body of the message
with debugging information.  This can be
used, for example, as a shadow transport
to watch the flow of mail for a while for
debugging purposes.  This essentially
allows for debugging without the ethical
and space problems of saving the
personal correspondence of others.
.BD dots boolean
If set,
then use the hidden dot protocol.
All output lines which begin with dot will
have one more dot prepended.
All of the various SMTP modes imply this behavior.
.BD driver string
The driver attribute names a specific set of low-level
functions which will do the work of delivering
mail.  This attribute is always required.
.BD error_transport string
names another transport that the message
should be sent to, if the first transport
returns failure.
.BD from boolean
If set,
then supply a ``From\fI<space>\fP'' line
before the message when delivering with
this transport.
If this is a remote transport
(i.e., the
.B local
attribute is not turned on)
then this line will end with ``remote from \fIhostname\fP''
where
.I hostname
is the UUCP name for the local host.
This is useful for delivery over UUCP and
for delivery to standard mailbox files,
which require this format.
.BD hbsmtp boolean
``Half-baked'' batched SMTP.
This is batched SMTP mode without
an initial HELO command or an ending QUIT command.
This can be used for creating files which will be concatenated
together at a later time to form one batch of
SMTP commands containing multiple messages.
Use of the
.B hbsmtp
attribute also turns on the
.B dots
attribute.
.BD local boolean
If set,
the form of the header and envelope information will be setup for
delivery to the local host.
This performs no changes to existing header fields,
other than insertion of commas into fields containing
sender and recipient addresses.
This also affects the form of any generated
``From\fI<space>\fP''
line and the form of envelope addresses used
in SMTP commands.
.BD max_addrs number
This states the maximum number of recipient addresses that can
be given in one call to the transport.
If this is turned off then there is no maximum number.
The default number is 1 and typically this is either
left as 1 or turned off.
.BD max_chars number
This states the maximum number of characters in recipient addresses
that can be given in one call to the transport.
If this is turned off then there is no maximum number.
The default number is about one third of the number characters that
can be passed as arguments to a program.
When using SMTP transports this should be turned off unless a remote
host is known to be unable to handle a large number of addresses.
For delivery over UUCP to a remote
.I rmail
program,
this should be around 200 or 250,
to avoid buffer overruns at the remote site.
UUCP generally has small buffers to hold argument information.

If
.I smail
is given an address whose length exceeds this number,
then the address will be passed with one call to the transport.
Thus,
this limit is not strictly enforced.
.BD max_hosts number
This states the maximum number of different hosts that can be given
in one call to the transport.
If this is turned off, using the form
.B \-max_hosts
then there is no maximum number.
The default number is 1 and typically this is
not changed.
.BD received boolean
If set,
then a
.B Received:
field is inserted for mail being delivered
with this transport.
The form of this field is taken from the
.B received_field
attribute in the
.I config
file.
This attribute is on be default.
.BD return_path boolean
If set,
then a
.B Return-Path:
field is inserted for mail being delivered
with this transport.
The form of this field is taken from the
.B return_path_field
attribute in the
.I config
file.
This should only be used for transports which
perform final delivery to local destinations.
.BD shadow string
This names another transport that the message
should be sent to.  This could be used
to, for example, start a program that
looked up the sender in a database and
brought up a rendition of his face
from a
.I "face server"
in a
window on your workstation.  The shadow
transport is called only if the
primary transport successfully performs
delivery.
.BD strict boolean
If this flag is set,
then some effort is done to transform
mail which does not conform to RFC822 standards.
This is potentially useful for sites which gateway
between the UUCP zone and the Internet.
In general,
it is not a good idea to turn this on as it
changes the contents of headers fields.
This should only be done when it is known that
some remote hosts only understand
mail which conforms to the
RFC822 standard.
.BD unix_from_hack boolean
If set then any line in the body of the message which begins with
``From '' will have the character `>' inserted at the beginning.
This is required for local delivery to mailbox files that are in
the standard form expected by the System V
.I mailx (1)
and the BSD
.I Mail (1)
programs.
.BD uucp boolean
If set then outgoing recipient addresses will be converted
into UUCP-style paths of the form
.IR hosta!hostb!hostc!user .
An exception is that any use of `%' as an address operator
is preserved.
Thus, an envelope address of
.I user%hostb@hosta
would be converted to
.IR hosta!user%hostb .
This only affects envelope addresses and does NOT affect
the message or the message header.
.SH "THE QUALIFY FILE"
This section details the format and use of the hostname
qualification file.

The qualify file defines the domain name(s) to be used in
making all hostnames fully-qualified.  Note that this file
is used only for bare hostnames, i.e. names without dots.

The qualify file uses the standard routine for reading
file entries.  Each entry should have the form:

.nf
	\fIhostname\fP  \fIdomain\fP
.fi

stating that the host name
.I hostname
should be considered a part of domain
.IR domain .
As a special case, if the
.I hostname
value is the special string ``*'',
the entry matches any host.
This is a catch-all feature which should
only be used in the last entry in a
qualify file.  Typically, UUCP sites
should should have an entry like:

.nf
	*         uucp
.fi

at the end of the qualify file.

If the qualify file is missing, or if no
entry is found that matches a given hostname,
then no hostname qualification is performed.
.SH "THE DIRECTOR DRIVERS"
This section details the usage and driver-specific
attributes for all of the director drivers
distributed with smail.
See the section
.B "THE DIRECTOR FILE"
for more information on directors.
.SH "The Aliasfile Driver"
The base standard for the format of the aliases and forward
files should be the format used by the BSD
.IR sendmail
program.
This format is simple yet powerful enough for most needs.

A sendmail-compatible aliases file consists of relations
between alias names and the lists of entities to that the
aliases expand.
Each entry is of the form:

.nf
	\fIalias-name\fP: \fIaddress\fP, ...
.fi

The following is a sample alias file for a machine nsavax:

.ta 0.5i 1i 3i
.nf
	# Sample aliasing file for nsavax
	root: brown, casey	# redirect root's mail
	MAILER-DAEMON: postmaster
	postmaster: brown	# brown maintains netnews and mail
	netnews: brown
	north: north, fawn	# copy fawn on all north's mail

	# post important information to network
	msgs: local-msgs@ciacray, local-msgs@nscprofs,
		local-msgs@nsavax
	local-msgs: "|/usr/ucb/msgs -s"	# deliver to msgs program

	# administrivia
	rnews: |/usr/lib/news/uurec	# read news messages from mail

	# mailing lists for accessing users on the local network
	nsavax-users: :include:/usr/lib/mail/nsavax-users
	ciacray-users: :include:/usr/lib/mail/ciacray-users
	nscprofs-users: :include:/usr/lib/mail/nscprofs-users

	# mail to everybody on the local network
	everybody: nsavax-users,	# well, almost everybody
		ciacray-users,
		nscprofs-users

	# save mail to mailing list requests and send to moderator
	funding-request: /usr/log/funding-req, reagan@nscprofs
	covert-bugs-request: /usr/log/covert-bugs-req, james.bond@ciacray

	# broadcast to mailing lists, and save a copy
	funding:	# excludes congress
		:include:/usr/list/funding,
		/usr/log/funding	# save all messages here
	covert-bugs:	# includes kgb
		:include:/usr/list/covert-bugs,
		/usr/log/covert-bugs	# save all messages here
.fi
.DT

The aliasfile driver searches for matches between a
local address on input and an
.I alias-name
from the alias file.
If a match is found, it returns the associated list.

It has the following driver attributes:

.BD file string
Define the name of the file containing the database.  Except when this
is not appropriate for the
.I proto
being used, if this does not
begin with ``/'', it will be referenced relative to the
.I smail_lib_dir
directory.
.BD interval number
A sleep interval between open retries, in seconds.
On systems which have 1 second granularities on wakeup
times and where, as a result,
sleep times can be nearly 0 seconds,
this number should be at least 2.
.BD modemask number
A mask, ala
.IR umask (2),
defining the
maximum permissiveness allowed for the
permissions on the alias file.  For example,
a modemask of 022 disallows write access
to all but the file owner.  This value should be chosen to
strike a reasonable compromise between security and user
convenience.  It should also take into account the use
of the
.B owners
and
.B owngroups
attributes described below.  A paragraph below describes the
consequences for a file not meeting this criteria.
.BD optional boolean
If set, then if the open fails, assume an empty
alias file.
This is useful for optional databases.
For example,
in a networking environment,
workstations may be configured with the option of having a private
alias file,
without the necessity of creating such a file on each host.
.BD owners string
A list of permissible owners for the alias file.  A paragraph below
describes the consequences for a file not meeting this criteria.
.BD owngroups string
A list of permissible owning groups for the alias file.  A paragraph
below describes the consequences for a file not meeting this criteria.
.BD proto string
Names the protocol used in opening and searching the database.
Possibilities are discussed below.
.BD reopen boolean
If this attribute is on,
the alias file will be closed and reopened after
each call to the driver.
This is useful for systems that have a shortage
of file descriptors yet wish to access a large number
of databases.
.BD retries number
the maximum count of open retries.  This should
be greater than zero if the system does not
have an atomic rename(2) system call, as the
alias file may not always exist while being
modified.
.BD tryagain boolean
If set, then if the open fails,
the resolution of local addresses will be attempted at a later time.
This is useful in a networking environment where failure
to open a database (such as a remote YP database) may be a result
of a server machine being down or temporarily inaccessible.
.PP
If any of the attributes
.BR modemask ,
.BR owners
or
.BR owngroups
reject the file as a possible security problem,
all addresses
returned are flagged with
the
.I caution
bit set.
See the generic director attribute
.B nobody
for more information.
.PP
The current list of possible values for the
.I proto
attribute is:
.TP 1i
bsearch
Use a binary search to look through a sorted file
arranged as lines which begin with a key and are
followed by the value associated with the key,
separated by a colon or whitespace.
.TP 1i
dbm
Use the BSD
.IR dbm (3x)
or
.IR ndbm (3x)
routines to
search for the key.  The keys and data in the dbm
database must end in a nul byte.  If only the
.IR dbm (3x)
library is available then only one dbm
database can be used by
.I smail ,
while the
.IR ndbm (3x)
routines will allow any number of databases.
However, it is always okay for multiple routers
and directors to use the same dbm database, if
this is useful.
.TP 1i
aliasyp
This is a variant of the
.I yp
protocol that is compatible with the standard Sun
.I mail.aliases
YP service.
This database has a different format from other databases
which must be taken into account when sending requests.
Typically this is not useful for a path database.
.TP 1i
lsearch
Use a linear search using the same read routine
used to read config files.  `#'-style comments are
allowed and the beginning of each file entry
should be the key, followed by whitespace or a
colon character.  The rest of the entry should be
the value associated with the key.
.TP 1i
yp
Use the Sun YP service to access a paths database
stored on a remote machine.
In this case the value for the
.B file
attribute is of the form:

.RS
\fIdomain_name\fP:\fIdatabase_name\fP
.RE

where the
.I domain_name:
is optional and defaults to the
default YP domain for the local host.
.PP
A simple entry in the director file is:

.nf
	# don't perform any authentication on the alias file
	aliases: driver=aliasfile;
		file=/usr/lib/aliases, proto=dbm
.fi
.SH "The Forwardfile Driver"
Sendmail-compatible forward files have the same structure as
mailing lists.
This format is:

.nf
	\fIaddress\fP, \fIaddress\fP, ...
.fi

Where newlines can be included wherever whitespace is allowed,
and where a `#' character begins a comment that ends at the
end of the line.
Comments are treated as whitespace.
.PP
An example forward file for the user james.bond on nsavax is:

.nf
	# send to my own machine, but keep a copy here
	# just in case it doesn't make it there.
	bond%british-ss@ciacray, james.bond
.fi
.PP
A useful forward file is:

.nf
	# I am on vacation, save away my mail, but tell people
	# I won't be back for a while
	hustead,
	"\||\|mailx \-s 'Yep, gone fishing!' \\"$SENDER\\" < $HOME/.fish"
.fi

Which will save to Ted Hustead's mailbox file and will also execute
the following shell command:

.nf
	mailx \-s 'Yep, gone fishing!' "$SENDER" < $HOME/.fish
.fi

where the shell variables $HOME and $SENDER are available from
the environment as the user's home directory and the sender
address, respectively.  Note that if the
.B ignore_write_errors
attribute is not turned on in the
pipe transport,
this example will cause mail to
be returned to the sender stating that a write error occurred
on the pipe to mailx.
To prevent this, the line could also be changed to:

.nf
	"\||\|cat>/dev/null;\\
	 mailx \-s 'Yep, gone fishing' \\"$SENDER\\"<$HOME/.fish"
.fi

where the ``cat>/dev/null'' will read
.BR stdin ,
preventing a write error on the pipe.
.PP
The current list of driver attributes for the forwardfile driver is:
.BD caution string
This string defines a list of users
and directories which should cause
addresses to be flagged with
.IR caution .
Each entry in the list is expanded individually.
If this string expansion fails,
it is ignored.
Typically,
this string is ``root'',
thus preventing file and shell command from
being performed as the superuser.
.BD checkowner boolean
If set, then one of the permissible
owners will be the user associated with the forward file.
.BD file string
The name of a file containing the forward
information for a user.  This string will be expanded
with the local name
passed to the director available as
.B $user
and
any associated home directory available as
.BR $HOME .
If this string expansion fails,
it is ignored.
.BD forwardto boolean
If set, then the file must begin with
``Forward to '' to be considered a forward file.
Also, only the first line is scanned for addresses.
This ``feature'' mimics the capability found in
some systems for hiding forwarding information
in user mailboxes.
.BD modemask number
A mode mask defining the maximum permissiveness
allowed for the permissions on a forward file.
Analogous to the modemask attribute for the
aliasfile driver.
.BD prefix string
This attribute requires that an address begin with the specified
string to be matched by the director.  In addition, any reference to
the
.B $user
variable in the file attribute will have this prefix removed.
.BD suffix string
This attribute requires that an address end with the specified string
to be matched by the director.  In addition, any reference to the
.B $user
variable in the file attribute will have this suffix removed.  Both a
.B prefix
and a
.B suffix
attribute can be specified for a director.  In this case both the
prefix and the suffix string are required for a match.
.BD owners string
Specifies a list of user who may own the
forward file.
.BD owngroups string
Specifies a list of groups who may own the
forward file.
.BD unsecure string
This string defines a list of users
and directories which should cause
addresses to be flagged with
.IR unsecure .
This will prevent delivery to shell commands or files.
Each list entry is expanded.
If this string expansion fails,
it is ignored.
.PP
If none of the attributes
.BR owners ,
.BR owngroups
or
.B checkowner
is given, no checks are made on ownership restrictions.  The
default modemask is 0, effectively disabling checks for file mode
restrictions.

.TP \w'NOTE:'+2n
NOTE:
Unless the file attribute references
.B $HOME
or begins with
``~/'' the forward file driver can be used to provide forward
files for users or names that are not listed in the passwd
file.  In this case,
.B $user
merely expands to the address
passed to the forwardfile driver.  This feature can be
used for setting up forwarding for obsolete accounts or
mailing list directories.
.PP
The
.B prefix
and
.B suffix
attributes can be used to define mailing list directories associated
with ownership or request addresses.  To get a directory of mailing
list or alias owners, a
.B prefix
of ``owner-'' could be used.  To create a directory of request
addresses, a
.B suffix
of ``-request'' could be used.
.PP
An example of useful forwardfile director entries are:

.nf
	# put forwarding addresses for obsolete accounts under
	# the /u/obsolete directory.  These will contain only
	# forwarding addresses.  This is maintained by users in
	# the group "admin" or "staff".
	obsolete:
		driver=forwardfile;
		file=/u/obsolete/$user,
		owngroups=admin:staff

	# handle per-user forward files in each user's home
	# directory.  This is roughly compatible with BSD
	# sendmail, though performs some access checks, and
	# is very cautious of directories which are remotely
	# accessible.  Root's .forward entries will operate
	# from the nobody uid.
	dotforward:
		driver=forwardfile, nobody;
		file=~/.forward, unsecure=~uucp:~ftp,
		caution=root, checkowner, owners=root,
		modemask=022

	# allow the "Forward to " feature to be used from user
	# mailbox files as used in System V.
	forwardto:
		driver=forwardfile, nobody;
		file=/usr/spool/mail/$user, caution=root,
		checkowner, modemask=002

	# define a mailing list directory, with any shell commands
	# executed under the nobody user id.  Any file in this
	# directory defines the name and contents of a mailing list.
	mailing_lists:
		driver=forwardfile, caution;
		file=/usr/lib/smail/lists/${lc:user}

	# define a directory of owner mailing lists.  Addresses
	# specified in this directory specify the owner address of a
	# mailing list or alias.
	owner_lists:
		driver=forwardfile, caution;
		file=/usr/lib/smail/lists/owners/${lc:user},
		prefix="owner-"
.fi
.SH "The Mailing-list Drivers"
Mailing-list drivers come in two forms, one form for mailing-lists
derived by aliasing drivers, and another form for mailing-lists
derived by forwarding drivers.  The reason for having two forms
is that security options take different forms depending on
where mailing-lists come from.  Also, by having them separately
recognized it is possible to allow pipes and files in
mailing-lists from alias files but not from forward files.  Note that if
a new driver is written that does not comply to the standards for
alias drivers and forwarding drivers, and that can produce mailing
lists, a new mailing-list driver may need to be written as well.
.PP
The format of a mailing list file is the same as that of a forward
file, a simple list of addresses, with optional comments.
.PP
The driver attributes are common to both of the mailing-list
drivers:
.BD copyowners boolean
If set,
attributes related to ownership restrictions
are taken from the director which produced
the mailing list address.
.BD copysecure boolean
The modemask is copied from the director which
produced the mailing list address.
.BD interval number
The sleep interval, in seconds, between retries.  For systems that
have a 1 second timing granularity, this number must be at least 2 to
guarrantee a non-zero sleep interval.
.BD match_director string
Names the specific director that this
entry matches expansions of.  This can be
used to assign different attributes from
alternate uses of the
.I aliasfile
and
.I forwardfile
directors.
.BD modemask number
The maximum permissiveness of file modes.
.BD owners string
A list of allowed owners.
.BD owngroups string
A list of allowed owning groups.
.BD retries number
The maximum count of open retries.
.SH "The User Driver"
The user director directs mail to a mailbox for known user
on the local host.  It will succeed if the local address
matches a user on the system and will put an entry on the list
of fully-resolved addresses.
.PP
The driver attributes are:
.BD prefix string
The prefix, if non-NULL, must be found in the front of the username
for this driver to be used.
This prefix is removed from the username prior to
determining if it is a valid user on the local host.
This can be used to set up an
alternate name for each user on the system
which is not matched by aliasing or forwarding
director.  Commonly,
.B prefix
will be set to
``real\-'' for one of the directors, so that
mail can be guaranteed to be delivered to a
user's mailbox file on a specific host by
mailing to an address such as
``real\-tron@namei.uucp.''
If a match is found,
the actual username is given to the transport.
.BD transport string
The name of the transport to associate with
the address.
.PP
A typical user director entry in the director file is:

.nf
	user:  driver=user; transport=local
.fi

This will associate any mail destined for a user on the
local host with the
.B local
transport.
.SH "The Smartuser Driver"
It may be that you wish all local addresses that you
don't recognize to be sent elsewhere.
For example, there could
be a host in your domain that knows where most of the domain's
users reside.
The
.I smartuser
driver is a convenient way of
handling this case, by redirecting mail for unknown users
to another host.
Note that this must be the last director
entry,
if it is used,
because it is generally non-discriminatory.
.PP
The possible driver attributes for the smart user driver are:
.BD new_user string
This defines the new address to direct mail
to.  This string will be string expanded
with
.B $user
set to the
local address name, and with
.B $HOME
being any the associated home directory,
if there is one.
It is a configuration error for this
string expansion to fail.
.BD well_formed_only boolean
If set, the
.I smartuser
driver only matches an address if it contains
characters exclusively from the set of
letters, digits, whitespace, as well as `\-',
`_', and `.'.
.PP
If the
.B well_formed_only
attribute is on,
any use of
.B $user
in the
.B new_user
value will have any groups of one or more whitespace
and dot are characters collapsed into exactly one dot.
If it is off, the
.B $user
value may be enclosed in double-quotes, with
backslash escapes where appropriate.
This prevents the the value of
.B $user
from changing the form of the address.
.PP
A sample entry is:

.nf
	smartuser:
		driver=smartuser;
		new_user=$user@gateway.domain,
		well_formed_only
.fi

With this entry, the input addresses:

.nf
	john
  and	John Q. Public
.fi

will become:

	john@gateway.domain
  and	John.Q.Public@gateway.domain

respectively.  If
.B well_formed_only
had not been set, the second
address would have been:

	"John Q. Public"@gateway.domain

whereas the input address:

	\\unusual"address"in\\deed

would become:

	"\\\\unusual\\"address\\"in\\\\deed"@gateway.domain 

Addresses which are produced by the smartuser driver are flagged
as such and will not themselves be matched by the smartuser
driver.  Thus, infinite loops will not occur if
``gateway.domain,''
from the example, happens to be the local host.
.PP
It is possible to set the new_user value in the
.I config
file.
This is done by setting the config
file attribute smart_user.  For example, the config file could
contain the following line:

.nf
	smart_user = $user@gateway.domain
.fi

Then, if the entry in the director file was:

.nf
	smart_user: driver=smart_user; well_formed_only
.fi

the configuration would be equivalent to the second
.I smart_user
example above.  This makes it possible to share copies
of the director file among several machines, with the smart user
configuration specific to one machine being set in its private
configuration file.
This config file attribute is used only if the
.I new_user
attribute is not given in the
.I smart_user
entry.
.SH "THE ROUTER DRIVERS"
This section details the usage and driver-specific
attributes for all of the router drivers
distributed with smail.
See the section
.B "THE ROUTER FILE"
for more information on routers.
.SH "The Pathalias Driver"
The pathalias router computes routes from a database in the
style produced by the pathalias program.  It has the following
driver-specific attributes:
.BD domain string
A list of domains to be stripped from the
end of a hostname before it is
searched for in the database.
Multiple
domains, in this list, are separated by colons.
.BD file string
This defines the name of the file containing
the database.  Except when it does not make sense as a result of the
.I proto
used, if this does not begin with ``/'', it will be referenced
relative to the
.I smail_lib_dir
directory.
.BD interval number
The number of seconds to wait between open retries.
.BD optional boolean
If set, then if the open fails, assume an empty
alias file.
This is useful for optional databases.
For example,
in a networking environment,
workstations may be configured with the option of having a private
alias file,
without the necessity of creating such a file on each host.
.BD proto string
Names the protocol used in opening and searching
the database.  Possibilities are discussed
below.
.BD reopen boolean
If set,
the pathalias will be closed and
reopened after each call to the pathalias
driver.  This is useful in
environments where file descriptors are
scarce but many databases are desired.
.BD required string
A list of domains which targets are
required to be for a match.  The names
are not stripped, unless they are also
specified by the
.B domain
attribute.
.BD retries number
The maximum number of retries for opening a
file.  This is useful on systems without an
atomic rename system call.  On such systems
there will be a window of vulnerability
when new databases are moved into place
where no file will exist.
.BD try string
A list of domains to be stripped only if
the target was not found in the database
without the domain stripped.
(This is currently not supported).
.BD tryagain boolean
If set, then if the open fails,
the resolution of local addresses will be attempted at a later time.
This is useful in a networking environment where failure
to open a database (such as a remote YP database) may be a result
of a server machine being down or temporarily inaccessible.
.PP
The current list of possible values for the
.I proto
attribute is:
.TP 1i
bsearch
Use a binary search to look through a sorted file
arranged as lines which begin with a key and are
followed by the value associated with the key,
separated by a colon or whitespace.
.TP 1i
dbm
Use the BSD
.IR dbm (3x)
or
.IR ndbm (3x)
routines to
search for the key.  The keys and data in the dbm
database must end in a nul byte.  If only the
.IR dbm (3x)
library is available then only one dbm
database can be used by
.I smail ,
while the
.IR ndbm (3x)
routines will allow any number of databases.
However, it is always okay for multiple routers
and directors to use the same dbm database, if
this is useful.
.TP 1i
lsearch
Use a linear search using the same read routine
used to read config files.  `#'-style comments are
allowed and the beginning of each file entry
should be the key, followed by whitespace or a
colon character.  The rest of the entry should be
the value associated with the key.
.TP 1i
yp
Use the Sun YP service to access a paths database
stored on a remote machine.
In this case the value for the
.B file
attribute is of the form:

.RS
\fIdomain_name\fP:\fIdatabase_name\fP
.RE

where the
.I domain_name:
is optional and defaults to the
default YP domain for the local host.
.TP 1i
aliasyp
This is a variant of the
.I yp
protocol that is compatible with the standard Sun
.I mail.aliases
YP service.
This database has a different format from other databases
which must be taken into account when sending requests.
Typically this is not useful for a path database.
.PP
All database lookups are either independent of case or, when case
independent lookups are impossible, case-folded.  Thus, keys
in DBM or YP databases must be in lower case.
.PP
As an example of the use of the
.BR domain ,
.BR try
and
.B required
driver attributes,
if the
.B domain
value is ``uucp,'' then any hostname that ends
in .uucp will have the .uucp removed before being looked up.
Alternately,
if
the the
.B try
value is ``uucp,''
then ``.uucp'' is
stripped only if the original
was not found.  If the
.B required
value is ``uucp'' then a hostname
is not a candidate for a match
unless it ends in ``.uucp.''  The effects of
.B domain
and
.B try
are
not cumulative and a hostname
is applied to the
.B required
attribute value before being applied to
.B domain
and
.B try
in that order.
.PP
Note that the length of any stripped string is added to the count
of characters matched for purposes of deciding which router had
the most complete match.
.PP
A sample pathalias router entry is:

.nf
	pathalias:
		transport=uux, driver=pathalias;
		file=paths, proto=bsearch,
		domain=uucp
.fi

An example of a pathalias file for the site
.I walldrug
is:

.ta .8i 2.5i
.nf
	.amdahl.com	amdahl!%s
	amdahl	amdahl!%s
	dgcad	namei!glotz!nsavax!dgcad!%s
	glotz	namei!glotz!%s
	hoptoad	hoptoad!%s
	kgbvax	kgbvax!%s
	kremvax	kremvax!%s
	namei	namei!%s
	nsavax	namei!glotz!nsavax!%s
.fi
.DT
.PP
This data base associates a host or domain name, on the left
hand side, with a path, on the right hand side.  The right hand
side should be a UUCP-style `!'-path ending in a ``%s''.
The format is
intended to be more general,
with the ``%s'' showing where to put
a user name.
Indeed,
.IR pathalias (X_MAN8_EXT_X)
can produce paths involving both
right and left operators such as:

.nf
	decwrl	decwrl!%s@ucbvax
.fi

This form is not recommended in general because of a historical
disagreement over the precedence of ``!'' and ``@''
which is not always resolved correctly by the pathalias program.
By standardizing on UUCP-style `!'-paths,
as will be produced from the
USENET maps, we avoid many routing ambiguities.
If the path is just ``%s,''
it denotes a name for the local host.
.SH "The Uuname Driver"
Some sites in the UUCP zone may wish to use a direct
path to their neighbors,
without relying on a pathalias
database.
Alternately,
a site may wish
to use the pathalias routes to their neighbors only in the case
that a domain address is given
(i.e., ``\fIneighbor\fP.uucp'').
.PP
A simple driver that meets these requirements is the
.B uuname
driver, which reads a list of hostnames from the output
of a shell command (normally
.BR /usr/bin/uuname )
and uses this list to match neighboring hostnames.
.PP
An example entry for a site that wishes to route to their
neighbors for hostnames that may end in .uucp is:

.nf
	uuname: transport=uux, driver=uuname;
		cmd=/usr/bin/uuname, domain=uucp
.fi

An alternative is a site that wishes to bypass the pathalias
router only for explicit target matches, so that
the form ``\fIneighbor\fP.UUCP''
will be routed through, as an example,
pathalias.
This can be done by not
specifying a domain, as in:

.nf
	uuname:  transport=uux, driver=uuname; cmd=/usr/bin/uuname
.fi

The
.I uuname
driver also supports the
.BR domain ,
.BR required
and
.B try
attributes,
and all three domain-style attributes can be
colon separated lists.  See the pathalias driver for more
details on these attributes.
.PP
In addition, there is a string attribute,
.B statfile
which names a file which can be used to determine when the output of
the shell command will change.  For example, when used with the uuname
command this would normally be either
.I /usr/lib/uucp/L.sys
or
.I /usr/lib/uucp/Systems
depending on whether a site is using HoneyDanBer or stock V7-style
UUCP.  If a
.B statfile
attribute is defined, then smail daemons that expect to deliver
multiple messages will cache the output of the shell command.  The
specified pathname will then be checked at regular intervals to
determine if the command should be reissued to refresh the cached
information.
.SH "The Queryprogram Driver"
If no other router driver meets a particular routing requirement, but
a shell script or C program can be written which does, the
.B queryprogram
driver can be used to access this script or program.  This driver runs
a program, with arguments, and examines its exit status and standard
output for information.  The program should return an exit status of
zero to indicate a match for the target host, non-zero otherwise.
Optionally, this program can write a path and a transport on its
standard output to provide additional information.  If a path is not
returned then a one-hop path to the target host is assumed.  The
program is always executed as an unprivileged user.
.PP
The
.B queryprogram
driver supports the
.BR domain ,
.BR required
and
.B try
attributes, as defined in the description of the
.B pathalias
driver.  The program and its arguments are described in terms of a
.B cmd
attribute which is a string consisting of white-space-separated tokens
which are expanded to form a program name and the arguments to pass to
that program.  The variable
.B $host
can be used to obtain the target host string.  White space or
punctuation from an expansion variable do not delimit arguments.
Two additional boolean attributes affect the driver's behavior:
.TP
.B read_path
If this attribute is enabled, then a path is read as the first
white-space delimited field in the first line of output from the
program.  If no output is produced by the program, or this attribute
is not enabled, then a one-hop path to the target host is assumed.  A
path should consist of a list of hostnames separated by an exclamation
point (`!') character.
.TP
.B read_transport
If this attribute is enabled, then a transport is read as a
white-space delimited field from the first line of output from the
program.  If the
.B read_path
attribute is also enabled, then the transport is taken from the second
field, otherwise it is taken from the first.  If no output was
generated by the program, or the field did not exist in the output,
then the normal methods for determining the transport are used.
.PP
A trivial example of the use of this driver is the router file entry:

.nf
	match_bar:
		driver=queryprogram, transport=bar;
		cmd="/bin/test X${lc:host} = Xfoo"
.fi

This router will use the program
.IR test (1)
to determine if the target host is
.IR foo .
If this is the target host, then it is assumed to be a neighboring
host which can be reached over the transport
.IR bar .
.PP
A more complex example is to create a shell script such as:

.nf
	# match_fubar.sh - match hosts on the fubar networks

	case "$1" in

	foo)	echo "foo foo_transport"; exit 0;;
	bar)	echo "foo!bar foo_transport"; exit 0;;
	curds)	echo "curds curds_transport"; exit 0;;
	whey)	echo "curds!whey curds_transport"; exit 0;;

	esac

	exit 1
.fi

By setting up a router file entry such as:

.nf
	match_fubar:
		driver=queryprogram;
		cmd="/bin/sh $lib_dir/match_fubar.sh ${lc:host}",
		read_path, read_transport
.fi

a complete, though not particularly optimal, router is created which
can match the hosts
.IR foo ,
.IR bar ,
.IR curds
and
.IR whey
and cause messages to these hosts to be delivered using one of the
transports
.IR foo_transport
or
.IR curds_transport .
.PP
The
.B queryprogram
driver is not very efficient, as it requires a fork/exec for each
host.  However, it is a very simple to construct a new router using
this driver, so it is useful for prototyping.  In general, a new form
of routing requirement is most efficiently handled by writing a new
router driver.
.SH "The Gethostbyname Driver"
In a networking environment,
hostnames on a
network can be matched using this driver,
which calls
the
.IR gethostbyname (3N)
library routine.
This routine is only
available on systems that supply a BSD compatible internet networking library.
The driver attributes for this driver are the
.BR domain ,
.BR required
and
.B try
attributes, which are compatible with the
.I pathalias
and
.I uuname
drivers.
.PP
.I gethostbyname
will only match a target host completely.
The hostname given to the transport will be the
host as given by the
.I h_name
field of the
.I hostent
structure.
.TP \w'NOTE:'+2n
NOTE:
The hostname given to
.IR gethostbyname (3N)
will be downcased,
so that upper-case or mixed-case names can be matched
correctly.
.SH "The Gethostbyaddr Driver"
Also in a network environment, it is useful to be able to
specify explicit Internet addresses using a target such as:
[192.2.12.3]
which is the internet address for the host
.IR eek.uts.amdahl.com .
.PP
The gethostbyaddr driver matches targets of this form,
which is defined
by square brackets surrounding only digits and dot characters.
The driver then converts this number into a hostname by
calling
.IR gethostbyaddr (3N)
to determine the proper name for the host.
If
.I gethostbyaddr
fails, then the input domain literal name is
given to the transport.
This is useful with incomplete host tables.
.PP
The gethostbyaddr driver has the following attributes:
.BD check_for_local boolean
If set, see if the hostname
returned by gethostbyaddr() matches
one of the known names for the
local host.  The name ``localhost''
is counted here as a potential name
for the local host.

NOTE:  This attribute is set by default.
.BD fail_if_error boolean
If set, then any domain-literal
target which does not fit the form
of an internet address is
considered an error.  If not set,
then such addresses are merely not
matched by the driver.
.SH "The Bind Driver"
The
.B bind
driver uses the
.I "Berkeley Internet Name Domain"
server,
.I named ,
to resolve target hostnames.  It is fully compliant with
the RFC974 standard,
.I "Mail Routing and the Domain System" ,
and uses MX and WKS records.  This router is available only on systems
that have a 4.3BSD compatible resolver library.  It is highly
recommended that this router be used for machines that are on the
internet, rather than using the
.B gethostbyname
router.
.PP
The following attributes vary the behavior of the
.B bind
driver:
.BD defer_no_connect boolean
If this boolean attribute is set, then we must be able to connect to
the server.  If attempts to connect to the server fail, then routing
is retried at a later time, on the assumption that the nameserver is
only down temporarily.  If this attribute is not set, then a failure
to connect to the server will cause the router to be ignored.  This
allows a bind router to be optional based on whether or not the server
exists.

NOTE:  This attribute is set by default.
.BD local_mx_okay boolean
If this boolean attribute is not set, then it is considered an error
for an MX resource record to be encountered which points to the local
host.  If this attribute is set, then such an MX resource record will
cause the address not to be matched.  The precedence number for the
resource record is taken into account here, so that an MX resource
record which points to the local host is ignored if there are other
records with a lower precedence number.
.BD defnames boolean
This boolean attribute is passed to the BIND resolve routines as the
RES_DEFNAMES flag.  If set, then hostnames which do not contain dots
will have a default domain appended to them before lookups.  For
example, this allows for hosts on a local area network to be
referenced using the basename of the host rather than requiring the
full domain name.

NOTE:  This attribute is set by default.
.PP
The bind driver will not partially match a hostname, even in the
presence of wildcarding MX resource records.  All matches are full
matches.
.PP
A site which exists only on the internet, requiring no other means of
routing should have a router file consisting of the entries:

.RS
.nf
# match internet address domain literals
internet_addrs:
	driver=gethostbyname, transport=smtp;
	fail_if_error
# match internet hostnames
internet_hosts:
	driver=bind, transport=smtp
.fi
.RE

A site which servers as the internet gateway for some set of hosts
should either have a paths file naming the hosts for which it
gateways, or should use the
.B local_mx_okay
attribute and allow target hostnames to fall through to a router for
another network.  For example, a UUCP network gateway which gateways
for a set of hosts listed int the UUCP map database distributed over
USENET could use the following two routers, in order, to handle all of
its gateway responsibilities:

.RS
.nf
internet_hosts:
	driver=bind, transport=smtp;
	local_mx_okay
uucp_hosts:
	driver=pathalias, transport=uux;
	file=/usr/lib/smail/paths
.fi
.RE

If the
.B defer_no_connect
is not used, then it is advisable to include a
.B gethostbyname
router to match hostnames.  The following sequence of routers will
allow the same smail configuration to be used on machines that do have
the BIND server and on machines that don't have the server:

.RS
.nf
internet_hosts:
	driver=bind, transport=smtp;
	-defer_no_connect
network_hosts:
	driver=gethostbyname, transport=smtp
.fi
.RE

.SH "The Smarthost Driver"
Sometimes it is handy to be able to redirect mail to
a host that you don't know about to some other host that has
more routing information.  This other host is
called a
.IR "smart host" ,
and can be named by using the smarthost driver.
.PP
The smarthost driver has the following driver attribute:
.BD path string
This define a host or UUCP-style `!'-path path that defines
the smart host.
.PP
If no
.B transport
or
.B method
attribute is given for the
router file entry,
this address will be resent through all
the routing drivers.
An exception is that an address cannot
be sent to the smarthost driver twice,
as this would mean that the path to the smarthost was not known.
.PP
For example, if the site
.I namei
wanted to use
.IR amdahl "'s"
routing
database for mail delivery to non-neighboring sites they could use
a router file entry of:

.nf
	smart_host: driver=smarthost;  path=amdahl

or	smart_host: transport=uusmtp, driver=smarthost;
		path=amdahl
.fi

.TP \w'NOTE:'+2n
NOTE:
At the present time, a
.B transport
or
.B method
attribute is required, as the software is not yet in place that
can rescan the routers in the required ways.
.PP
Then, a recipient address of
``Ted.Husted.Jr@walldrug.uucp''
will be
rewritten so that the hostname is
.I amdahl
and the
remaining part of the address is
``Ted.Hustead.Jr@walldrug.uucp.''
Alternately, in the second form for the
entry,
the transport,
.IR uux,
would
be known immediately and be passed
the hostname ``amdahl'' immediately,
with a
.B $user
value of
``Ted.Hustead.Jr@walldrug.uucp.''
.PP
By specifying a UUCP-style `!'-path it is possible to route mail to a
smart host that you would not otherwise be able to route to.
For example, if the machine
.I glotz
wished to use
.I amdahl
as its smart host, through its neighboring site
.IR namei ,
it could use: 

.nf
	smart_host: driver=smarthost; path=namei!amdahl

or	smart_host: transport=demand, driver=smarthost;
		path=namei!amdahl
.fi

It is possible to set the path and/or the transport in the
.I config
file.  This is done by setting the
config file attributes
.B smart_path
and
.BR smart_transport .
For example, the config file could contain the following:

.nf
	smart_path = amdahl
	smart_transport = uusmtp
.fi

Then, if the entry in the router file was:

.nf
	smart_host: driver=smarthost
.fi

the configuration would be essentially the same as in the second
smart_host example above.  This makes it possible to share copies
of the router file among several machines, with the smart host
configuration specific to one machine being set in its private
configuration file.
.PP
These config file attributes are used only if the path driver
attribute is not given in the
.I smart_host
entry.
If the
.B smart_path
attribute from the config file is used, the
.B smart_transport
will override a
.B transport
or
.B method
attribute.
.SH "THE TRANSPORT DRIVERS"
This section details the usage and driver-specific
attributes for all of the transport drivers
distributed with smail.
See the section
.B "THE TRANSPORT FILE"
for more information on transports.
.SH "The Pipe Driver"
The pipe driver is the most general form of transport.  Its
job is to send mail messages to another program, such as
.IR uux (1)
or
.IR sh (1).
.PP
The driver attributes for the pipe
driver are:
.BD cmd string
The program to be run and the arguments
to be passed.
This is string expanded.
To handle multiple addresses being given
to a transport,
the use of
.B $(
and
.B $)
can be used to bracket a section of the
command string which is to be repeated for
each address given to the transport.
It is a configuration error for string expansion
to fail.
.BD defer_child_errors boolean
Generally, only child failures from
the signal SIGTERM are reattempted
at a later time.
If this
is set, then retries are performed at a later time if the
exit code is non-zero, or if the write
failed on the pipe.
This is useful for treating errors from
UUCP as configuration or as
temporary filespace problems.
.BD group string
The name of the group to
.IR setgid (2)
to within
the child process.  Useful only if the
mailer is running as root.
.BD ignore_status boolean
If set, the exit status of the child process is
ignored.  If this is not set, an exit
value other than 0 is noted and mail is
sent to the postmaster stating this.
.BD ignore_write_errors boolean
If set, write errors are ignored.  This
is useful for running programs that may
not actually read their standard input.
If this is not set, a write error will
cause mail to be returned to the sender.
.BD log_output boolean
The
.I stdout
and
.I stderr
of a command are
logged and returned to the sender in case
of problems.
The current implementation is not very good
as it actually returns the logs for all such transports
in the event that any transports fail.
This attribute is on by default.
.BD parent_env boolean
Stuff the environment with data taken
from the parent of the input address,
rather than the input address itself.
This is useful for the
transport specifically named
.I pipe
which is used by smail for delivery
to shell-command
addresses.
Here the recipient address stored into
the environment will then be the address
that produced the
shell-command address,
rather than the shell-command address itself.
.BD pipe_as_sender boolean
If set, the child process' uid is taken
from the real uid at the time the message was
read by
.IR smail .
This does not affect the
group id for the child.  This overrides
the uid obtained from the
.B pipe_as_user
attribute.
.BD pipe_as_user boolean
Obtain a
.I uid
and,
if `group' attribute is not given,
a
.I gid
associated with the
address (such as the user for a .forward file).
Then set these via
.IR setuid (2)
and
.IR setgid (2)
in the child process.

NOTE:  This attribute is on by default.
.BD umask number
file creation mask for the child process.
.BD user string
The name of the user to
.IR setuid (2)
to within
the child process.  Useful only if the
mailer is running as root.
.PP
The environment of the child process is entirely initialized
and loaded with variables which may be useful in shell scripts
or intelligent mail processing programs.  Exactly one
environment variable is passed through from the environment
handed to the
.I smail
program:  the
.B TZ
variable defining the
timezone.
The following portion of the environment is
independent of the recipient addresses:

.ta 1.5i
.nf
BASENAME	the basename for the spool file
GRADE	the grade character
MESSAGE_ID	the message ID as assigned by \fIsmail\fP
PATH	``/bin:/usr/bin''
PRIMARY_NAME	the official name for the host
SENDER	the sender address
SHELL	``/bin/sh''
SPOOL_FILE	the complete name for the spool file
UUCP_NAME	the name for the host on the uucp network
VISIBLE_NAME	the name for the host used in addresses
.fi
.DT

The rest of the environment is loaded from the input address,
or from the parent of the input address:

.TP \w'PRIMARY_NAME'+1n
ADDR
The recipient address
(or one of the recipient addresses, if more than one is
given to the driver).
.TP \w'PRIMARY_NAME'+1n
HOME
The home directory (or one of home
directories, if more than one recipient
address is given to the driver).  If no
home directory is associated with an
address, ``/'' is used.
.TP \w'PRIMARY_NAME'+1n
HOST
The recipient hostname (or one of the
recipient hosts, if more than one host is
given to the driver).
.TP \w'PRIMARY_NAME'+1n
USER, and LOGNAME
These two variables are loaded with the name
of a user on the local host, if one is found
with some association to the address.
.PP
Examples of the use of the pipe driver are:

.nf
	# transport used for delivery to shell-command addresses
	pipe:	from, local, return_path, unix_from_hack,
		driver=pipe;
		cmd="/bin/sh \-c $user",
		pipe_as_user, ignore_status,
		ignore_write_errors, parent_env,
		\-log_output

	# delivery to a remote \fIrmail\fP(8) program using \fIuux\fP(1)
	uux:	max_addrs=5, max_chars=200, from, received,
		driver=pipe;
		cmd="/usr/bin/uux \- \-r \-g$grade $host!rmail
			$((${strip:user})$)",  # see ``String expansion'' above
		pipe_as_sender
.fi
.SH "The Appendfile Driver"
The appendfile driver creates or appends to files.  It can either
write to a filename derived from the recipient address, or it
write a unique file into a directory.  This latter capability can
be used to implement a primitive output queue for some purposes.
.PP
The driver-specific attributes are:
.BD append_as_user boolean
Get the
.I uid
and, perhaps, the
.I gid
from
the user id and group id associated with
the address.
For example, the user
associated with a forward file
might be used.
This attribute is on by default.
.BD check_path boolean
If set, then verify the permissions on a
complete path for a file or dir attribute.
This requires that all directories leading
to a file must be searchable by the
appending user (see the
.IR user ,
.I group
and
.I append_as_user
attributes).
Under System V,
this requires a
.IR stat (2)
call for each
directory in the path, and is thus somewhat expensive.
.BD check_user boolean
Reject an address if the
.B $user
would contain a `/'.
This prevents a
.B $user
expansion
from accessing a different directory.
.BD dir string
Defines a directory in which to write
unique files.  Files written to this
directory always begin with the letter `q',
while temporary files used in the creation
process begin with ``temp.''  This string is
expanded similarly to the
.B file
attribute.
It is a configuration error for this string expansion
to fail.
.BD expand_user boolean
If set the value for
.B $user
value is string expanded
before the value for the
.B file
or
.B dir
attribute is expanded.
This is useful if a local-form address may
require
`~' or `$' expansions.
.BD file string
Defines a file to append messages to.
This string is expanded,
and the variables
.B $user
and
.B $host
are set
from the recipient address.
It is a configuration error for this string expansion
to fail.
.BD group string
become this group.  Similar to the
.B user
attribute.
.BD mode number
When creating a file,
.IR creat (2)
it with this access mode.
The default is 0666.
.BD prefix string
This prefix is inserted in the file
before the message.  This string is
expanded, with
.B $user
and
.B $host
being available from the
recipient address.
It is a configuration error for this string expansion
to fail.
.BD suffix string
This suffix is appended to the file after
the message.
This string is expanded, with
.B $user
and
.B $host
being available from the recipient
address.
It is a configuration error for this string expansion
to fail.
.BD user string
This become this user (effectively at least)
when opening or creating the file.  Access
permissions are checked relative to this
user, and the user will own the file if it
did not previously exist.
.PP
To better understand the use of some of these attributes,
consider the transport file entry:

.nf
	file:	driver=appendfile, from, return_path, local;
		file=$user, suffix="\\n", check_path,
		expand_user, append_as_user, mode=0664
.fi

This transport will be called when a file address is
produced by a director.  Such addresses should be expanded,
because they may require
`~' expansions.
Also, to keep standard many user agents happy,
an extra newline is inserted after each message.
The
.B append_as_user
attribute is set
to ensure that addresses produced from,
say,
a forward file are only created or appended to if
the associated user has permissions to do so.
Because these filenames can be arbitrary,
.B check_path
is set to make sure that an otherwise
inaccessible directory is not written to.
.PP
When given an address of ``~/Incoming,'' with an associated
home directory of ``/u/joe-user'' and an associated user of
.IR joe-user ,
the following steps occur:
.TP 3n
a.
The
.B $user
variable is expanded to ``/u/joe-user/Incoming.''
.TP 3n
b.
The
.B file
attribute is also expanded to ``/u/joe-user/Incoming.''
.TP 3n
c.
The directories
.BR / ,
.B /u
and
.B /u/joe-user
are checked
for accessibility by the user
.IR joe-user .
If any of these
is not searchable, then delivery fails.
.TP 3n
d.
The file
.B /u/joe-user/Incoming
is opened for append access.
If it does not exist, it is created, will be owned by
.I joe-user
and will have mode 0664.
Creation will fail if
.I joe-user
cannot write the directory.
.TP 3n
e.
The message is written with a local-form ``From\fI<space>\fP'' line.
.TP 3n
f.
An extra newline is appended to the file, after the
message.
.TP \w'NOTE:'+2n
NOTE:
.I smail
will follow the local conventions on locking
protocols for mailbox files, which may involve creating
a
.RB . lock
file or using a file lock system call,
such as
.IR lockf (3)
under System V of
.IR flock (2)
under BSD.
.PP
Next, lets examine:

.nf
	local:	driver=appendfile, local, from, return_path;
		file=/usr/spool/mail/$user, append_as_user,
		check_user, mode=0600
.fi

In this example, the
.B $user
value is not expanded before expanding
the
.B file
attribute.  Also, just to make sure,
.B $user
is
verified to not contain a `/'.
Given an input address of
``jane-doe,''
associated with the user
.IR jane-doe ,
mail will be appended to the file
``/usr/spool/mail/jane-doe.''
If it did not
previously exist, it will be owned by
.I jane-doe
and will have
a mode of 0600.
.SH "The TCPSMTP Driver"
Simple support exists in
.I smail
for delivery using SMTP over
TCP/IP,
for systems that have BSD compatible networking.
It is intended that eventually a complete
backend will exist to handle SMTP in a more efficient manner,
though in the mean time a built-in SMTP transport driver is
available.
.PP
The smtp driver can be used for delivery of any number
of addresses to one remote host, where the remote host can be
specified either in form of a hostname known by the networking
software or by an internet number in square brackets, such as
.IR [192.2.12.142] .
For example, the routing drivers
.B gethostbyaddr
and
.B gethostbyname
are suitable for matching addresses to be
delivered using the SMTP driver.
.PP
The attributes for the tcpsmtp driver are:
.BD short_timeout interval
This defines the response timeout for oerations that are assumed to
be short, such as protocol startup and protocol exit.  This can use
suffix letters of `s', `m', `h', and `d' to mean seconds, minutes,
hours or days, with no suffix signifying seconds.  Times can be added
through direct concatenation.  For example, the value `5m30s'
signifies 5 minutes and 30 seconds.
The default value is 5 minutes.
.BD long_timeout interval
This defines the response timeout for long operations, i.e., those
that are not short.  Suffix letters can be used in the same manner as
with
.BR short_timeout .
The default value is 2 hours.
.BD service string_or_number
This attribute identifies a TCP/IP port number, either directly as a
number, or as a name to be searched for in the
.I /etc/services
file.  This port number will be used in connecting to the remote host.
The default is
.IR smtp .
.PP
The smtp driver attempts to connect immediately and deliver a
single message.  If access to the remote host is currently not
possible, the driver will tell smail that delivery should be
attempted at a later time.
.PP
An example of the use of the smtp driver is the entry:

.nf
	# deliver using SMTP over TCP/IP to the remote host
	tcpsmtp: \-max_chars, \-max_addrs, driver=smtp
.fi

If your site is on the Internet and gateways from the UUCP
zone, it may be reasonable to set the
.B strict
attribute.
Otherwise, this is probably not a good idea.

If the
.B local
attribute is not set, then the envelope sender
address passed to the remote host will always contain the
primary name for the local host, while the recipient addresses
passed in the envelope will always be in RFC822 mailbox form
or route addr form.  This is in keeping with the RFC821 SMTP
standards document.
.PP
The smtp driver always sets the
.B crlf
and
.B dots
transport attributes.
.SH "DEFAULT CONFIGURATION"
The default internal configuration is defined in the source files
.I config.h
and
.IR default.c .
The default director configuration uses:
.IP \fIaliases\fP
an alias database stored as an ASCII text file in
.I "X_PATH_ALIASES_FILE_X"
.IP \fIdotforward\fP
forward files stored in user home directories in the file
.I .forward
.IP \fIforwardto\fP
forwarding information stored in user mailbox files
preceded by the string ``Forward to ''
.IP \fIuser\fP
matches local users with delivery using the
.I local
transport
.IP \fIreal_user\fP
matches local users with a prefix of
``real-'' with delivery  (bypassing forwarding) using the
.I local
transport
.IP \fIlists\fP
mailing lists stored in the directory
.I "X_LIB_DIR_X/lists/"
.IP \fIsmart_user\fP
a smart-user director may also be defined.
.PP
The default router configuration uses:
.IP \fIinet_addrs\fP
match domain literals forming IP internet addresses,
deliver with the transport
.IR smtp ;
configured in if BSD style internet networking is available
.IP \fIinet_hosts\fP
call
.I gethostbyname
to match hosts on an IP network,
deliver with the transport
.IR smtp ;
configured in if BSD style internet networking is available
.IP \fIpaths\fP
a pathalias database stored as a sorted ASCII file in
.I "X_LIB_DIR_X/paths"
.IP \fIuucp_neighbors\fP
resolution of neighboring hosts on a UUCP network by calling
the program
.I uuname (1)
.IP \fIsmart_host\fP
a smarthost router may also be defined.
.PP
The default transport configuration defines:
.IP \fIlocal\fP
delivery to local users,
either by appending directly to their mailbox files or
by calling the program
.I /bin/mail
to deliver for us
.IP \fIpipe\fP
deliver to shell command addresses by invoking
/bin/sh
.IP \fIfile\fP
deliver to file addresses by appending to them directly
.IP \fIuux\fP
deliver to remote hosts by invoking
.IR uux (1)
to deliver to a remote
.I rmail
program;
the
.B \-r
flag is supplied to prevent an immediate poll
.IP \fIdemand\fP
this is similar to
.I uux
except that the
.B \-r
flag is not supplied, thus generating an immediate attempt
to poll the remote site
.IP \fIsmtp\fP
attempt to make a TCP/IP connection to a remote
host and deliver mail using an interactive SMTP protocol;
configured if BSD style internet networking is available
.IP \fIuusmtp\fP
send batched SMTP commands to remote hosts by invoking
.IR uux (1)
to deliver to a remote
.I rsmtp
program;
the
.B \-r
flag is supplied to prevent an immediate poll
.IP \fIdemand_uusmtp\fP
this is similar to
.I uusmtp
except that the
.B \-r
flag is not supplied, thus generating an immediate attempt
to poll the remote site
.SH FILES
The following files and directories are from
a typical
.I smail
configuration:

.PD .2v
.TP 2.1i
.I "X_LIB_DIR_X/config"
Optional general
.I smail
configuration.
This file can override compiled-in
configuration.
.TP 2.1i
.I "X_LIB_DIR_X/transports"
Optional configuration for
.I smail
transports;
i.e., configured methods of mail delivery.
This file replaces the compiled-in
transport configuration.
.TP 2.1i
.I "X_LIB_DIR_X/directors"
Optional configuration for
.I smail
directors,
i.e., configured methods for resolving
local addresses.
This file replaces the compiled-in
director configuration.
.TP 2.1i
.I "X_LIB_DIR_X/routers"
Optional configuration for
.I smail
routers,
i.e., configured methods for resolving
or routing to remote hosts.
This file replaces the compiled-in
router configuration.
.TP 2.1i
.I "X_LIB_DIR_X/aliases"
A file of aliases for local addresses.
.TP 2.1i
.I "X_LIB_DIR_X/paths"
A file of paths to remote hosts.
.TP 2.1i
.I "X_LIB_DIR_X/lists/"
A directory of mailing list files.
.TP 2.1i
.I ~/.forward
Lists of forwarding addresses for
local users.
.TP 2.1i
.I "X_MAIN_SPOOL_DIR_X"
The top of the spool directory hierarchy.
.TP 2.1i
.I "X_MAIN_SPOOL_DIR_X/input"
The directory containing messages to
be processed and delivered.
.TP 2.1i
.I "X_MAIN_SPOOL_DIR_X/msglog"
A directory of transaction logs
for individual messages.
.TP 2.1i
.I "X_MAIN_SPOOL_DIR_X/lock"
A directory used in
.I smail
input spool files.
.TP 2.1i
.I "X_LOGFILE_X"
A log of smail transactions.
.TP 2.1i
.I "X_PANICLOG_X"
A log of configuration or system errors encountered by
.IR smail .
.TP 2.1i
.I "X_MAIN_SPOOL_DIR_X/error"
Messages that failed due to a small set of fatal
error such as a configuration error are placed
in this directory.
Currently the site administrator must move these back into
.I "X_MAIN_SPOOL_DIR_X/input"
when the error condition is resolved.
.TP 2.1i
.I "X_MAILBOX_DIR_X"
The directory for user mailbox files.
.PD
.SH "SEE ALSO"
.IR binmail (1),
.IR mailx (1)
under System V,
.IR Mail (1)
under BSD,
.IR resolver (3),
.IR named (8),
.IR pathto (X_MAN1_EXT_X),
.IR smail (X_MAN8_EXT_X),
.IR "Smail Administration and Installation Guide" ,
.IR "Smail Design Document" ,
DARPA Internet Requests for Comments,
RFC821, RFC822, RFC974 and RFC976.
.SH BUGS
There should probably be a way to specify different
exit codes as causing different actions on the part of
.IR smail .
.PP
Colons cannot be included in the value of a list element.
.PP
Strings such as "100K" or "100" are interpreted as numeric values
when assigned to numeric variables, and are interpreted as strings
when assigned to a string variable.
.SH COPYRIGHT
Copyright(C)1987, 1988 Ronald S. Karr and Landon Curt Noll
.br
See a file COPYING,
distributed with the source code,
or type
.I "smail -bc"
for distribution rights and restrictions
associated with this software.
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