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.TH SMAIL 8
.SH NAME
smail, rmail \- UUCP mailer with routing
.SH SYNOPSIS
.B smail
[ options ] address ...
.br
.B rmail
[ options ] address ...
.SH DESCRIPTION
The
.I smail/rmail
program replaces
.IR /bin/rmail (1)
to become the UUCP mail transport mechanism.
They are links to the same executable.
.I rmail
receives mail from UUCP,
.I smail
introduces mail into UUCP.
.PP
.I smail/rmail
can work with or without
.IR sendmail (8),
or another intelligent mail system.
For hosts with just
.IR /bin/mail (1),
.I smail/rmail
subsumes some of the functions of
.I sendmail,
and hands only local mail to
.I /bin/mail.
For hosts with
.I sendmail,
.I smail/rmail
can act as UUCP front and back ends to
.I sendmail,
allowing
.I sendmail
to process all mail through the host.
As distributed, 'bang' mail that is not bound for a local
recipient will be passed directly to
.I uux
without calling
.I sendmail.
.PP
To varying degrees,
.I smail/rmail
automatically routes the addresses it processes.
.I smail/rmail
most often routes domain style addresses (i.e. user@domain), producing
a UUCP path (i.e. host!address) or a local address (i.e. user), but it can
also reroute explicit UUCP paths.
.SH OPTIONS
.TP
.B \-d
Be verbose and don't invoke other mailers.
.TP
.B \-v
Be verbose, but still invoke other mailers.
.TP
.BI \-h " hostname"
Set hostname.  The default is configuration dependent, but usually provided
by a system call such as
.IR gethostname (2)
or
.IR uname (2).
.TP
.BI \-H " hostdomain"
set hostdomain.  The default is configuration dependent.
.TP
.BI \-p " pathfile"
Set path database file name if not /usr/lib/uucp/paths.
.TP
.BI \-a " aliasfile"
For sites without sendmail, set alias database file name if not in /usr/lib/aliases.
.TP
.BI \-q " number"
Take
.I number
as the queueing threshold.
When routing mail (
.I -r, -R,
or domain addressed mail
) to a given host, if the cost listed in the
.I paths
file is less than the queueing threshold, then the mail
will be sent immediately.  This overrides the default threshold
(see QUEUECOST in defs.h) of DEDICATED+LOW.
.TP
.BI \-u " uuxflags"
Use
.I uuxflags
as the flags passed to uux for remote mail.
This overrides any of the default values and other queueing strategies.
.TP
.B \-r
Route the first component of a UUCP path (host!address) in addition to routing
domain addresses (user@domain).
.TP
.B \-R
Reroute UUCP paths, trying successively larger righthand substrings
of a path until a component is recognized.
.TP
.B \-l
Instead of routing a domain address, send it to the local mailer for
processing.  Normally, only local addresses go to the local mailer.
.TP
.B \-L
Send all addresses to the local mailer for processing, including UUCP paths.
.PP
Most of the flags are also compile time options, since
.I uux
does not normally invoke
.I rmail
with the desired flags.
.I smail
resets any preset
.B -l
or
.B -L
flags.
.B -l
flag causes 
.B rmail
to send all domain addresses through the local mailer,
to process addresses for non UUCP domains.
The
.B -L
flag causes
.B rmail
to send even explicit UUCP paths through the local mailer,
presumably to make use of other transport mechanisms.
In both cases, rmail defers any routing until smail gets hold it.
.SH ADDRESSES
.I smail/rmail
understands "user@domain" to be a domain address, "host!address" to be a
UUCP path, and anything else to be a local address.
.PP
Because hostile
.I rmail's
unpredictably interpret mixed UUCP/domain addresses,
.I smail/rmail
understands "domain!user" to be a domain address, and generates
"path!domain!user" when mailing to a cognate
.I smail/rmail
host.
To distinguish domain "domain!user" from UUCP "host!address", "domain"
contains at least one (1) period.
Unlike the old
.I /bin/rmail,
.I smail/rmail
gives precedence to @ over ! when parsing mixed addresses,
thus a!b@c is parsed as (a!b)@c, rather than a!(b@c).
.SH ROUTING
Because
.I smail/rmail
is the UUCP transport mechanism, it can only effect delivery on UUCP paths 
and local addresses; domain addresses require resolution into UUCP paths or
local addresses.  
To resolve a domain address,
.I smail/rmail
finds a route to the most specific part of the domain specification listed
in the routing table.
Two degrees of resolution can occur:
.RS
.PP
Full resolution:
.I smail/rmail
finds a route for the entire domain specification, and tacks the user
specification onto the end of the UUCP path.
The address can also fully resolve to a local address (the UUCP path is null).
.PP
Partial resolution:
.I smail/rmail
finds a route for only righthand part of the domain specification, so it 
tacks the complete address (in the form domain!user) onto the end of the 
UUCP path.
Since this syntax is not widely understood, UUCP gateways listed in
the path database must install new UUCP software, either
.I smail/rmail
or new
.I sendmail
configuration files (or both).
.RE
.PP
It is an error if a partially resolved address routes to the local host 
(a null UUCP path), since according to the routing table, the local
host is responsible for resolving the address more fully.
.PP
The
.B -r
flag causes
.I smail/rmail
to attempt to route the first component of a UUCP path, probably so it
can impress people with how many UUCP hosts it knows.
If this fails, it passes the unrouted address to
.I uux,
in case the path database is not complete.
The 
.B -R
flag causes
.I smail/rmail
to take a UUCP path and route the rightmost component of the path (save
the user name) possible.
This is mostly for hosts that have very up-to-date routing tables.
.PP
If a route cannot be discerned from the available routing database,
then one more attempt to route the mail is made by searching for an
entry in the database for a route to a
.I smart-host.
If this entry exists, then the mail will be forwarded along that route
to be delivered.  This allows a host to depend on another, presumably
better informed, host for delivering its mail.
This kind of arrangement should be worked out,
.I in advance,
with the
.IR smart-host 's
administrator.
.PP
After
.I smail/rmail
resolves an address, it reparses it to see if it is now a UUCP path or
local address.  If the new address turns out to be another
domain address, smail complains because we don't like to resolve more than once.
This error occurs when an address partially resolves the local host.
.PP
By default,
.I smail
will not alter the explicit bang path routing of any mail message.
If the stated path is unuseable, (i.e., the next hop host is unknown)
then smail will apply ALWAYS routing, and attempt to deliver the mail
to the potentially new address.  If this fails too, then REROUTE routing
will be applied to the address, and another attempt to deliver is made.
Lastly, an attempt to find a path to a better informed host
.I smart-host
will be made and the mail passed to that host.
.SH FROMMING
.I smail/rmail
collapses From_ and >From_ lines to generate a simple from argument, which
it can pass to
.I sendmail
or use to create its own "From" line.
The rule for fromming is: concatenate each "remote from" host (separating 
them by !'s), and tack on the address on the last From_ line; if that address 
is in user@domain format, rewrite it as domain!user; ignore host or
domain if either is simply the local hostname.  It also removes redundant
information from the From_ line.  For instance:
.sp
.ce
 ...!myhost!myhost.mydomain!...
.sp
becomes
.sp
.ce
 ...!myhost!...
.sp
Leading occurrences of the local host name are elided as well.
.PP
.I smail/rmail
generates it own From_ line, unless it is feeding
.I sendmail,
which is happy with the
.BI -f from
argument.
For UUCP bound mail,
.I smail/rmail
generates a "remote from hostname", where hostname is the UUCP hostname
(not the domain name), so that From_ can indicate a valid UUCP path, leaving
the sender's domain address in From:.
.SH HEADERS
Certain headers, To:, From:, Date, etc., are required by RFC822.
If these headers are absent in locally generated mail, they will
be inserted by smail.  Also, a line of trace information, called
a Received: line, will be inserted at the top of each message.
.SH UNDELIVERABLE MAIL"
Although nobody likes to have a mail message fail to reach its
intended destination, it somtimes happens that way.
Mail that is found to be undeliverable
(i.e., unknown user or unknown host)
will be returned to the sender.
.SH FILES
/usr/lib/uucp/paths		ascii path database
.br
/usr/lib/aliases		ascii alias database
.br
/usr/spool/uucp/mail.log		log of mail
.br
/tmp/mail.log			record of mail
.SH AUTHOR
Christopher Seiwald
.br
chris@cbosgd.att.com
.SH SUPPORT
Enhancements, enhancement requests, trouble reports, etc.,
should be sent to
.sp
.ce
uucp-problem@cbatt.att.com.
.sp
.SH "SEE ALSO"
.IR uux (1),
.IR paths (8),
.IR aliases (8)
.br
.IR sendmail (8)
.br
.IR binmail (1)
on BSD systems only
.br
.IR mail (1)
on System V systems
.SH VERSION
@(#)smail.8	2.2 smail 1/11/87