.TH qmail-smtpd 8
.SH NAME
qmail-smtpd \- receive mail via SMTP
.SH SYNOPSIS
.B qmail-smtpd
.SH DESCRIPTION
.B qmail-smtpd
receives mail messages via the Simple Mail Transfer Protocol (SMTP)
and invokes
.B qmail-queue
to deposit them into the outgoing queue.
.B qmail-smtpd
must be supplied several environment variables;
see
.BR tcp-environ(5) .

.B qmail-smtpd
is responsible for counting hops.
It rejects any message with 100 or more 
.B Received
or
.B Delivered-To
header fields.

.B qmail-smtpd
supports ESMTP, including the 8BITMIME and PIPELINING options.
.SH TRANSPARENCY
.B qmail-smtpd
converts the SMTP newline convention into the UNIX newline convention
by converting CR LF into LF.
It returns a temporary error and drops the connection on bare LFs;
see
.BR http://pobox.com/~djb/docs/smtplf.html .

.B qmail-smtpd
accepts messages that contain long lines or non-ASCII characters,
even though such messages violate the SMTP protocol.
.SH "CONTROL FILES"
.TP 5
.I addrcheck.cdb
A database of acceptable mailboxes.  If present, this is used to report
erroneous RCPT TO commands, which can reduce the amount of junk mail
accepted.  It contains an encoding of the virtual domains map
.RB ( \c
.BI V domain
maps to 
.IR prefix ),
the local domains
.RB ( \c
.BI @ domain
maps to an empty string), and the available local parts
.RB ( \c
.BI L mailbox
maps to
.B +
if the address is valid or
.B \-
if not).  It's best made using
.BR qmail-valid-addresses (8).
.TP 5
.I addrcheck-delay
Delay in seconds before reporting bad mailbox names after the 
.I addrcheck-slow
limit is reached.  The default is 2.
.TP 5
.I addrcheck-limit
Number of bad mailbox names to tolerate before dropping the connection.
Zero means an infinite number.  The default is 50.
.TP 5
.I addrcheck-slow
Number of bad mailbox names to tolerate before imposing delays.  The
default is 5.
.TP 5
.I badmailfrom
Unacceptable envelope sender addresses.
.B qmail-smtpd
will reject every recipient address for a message
if the envelope sender address is listed in
.IR badmailfrom .
A line in
.I badmailfrom
may be of the form
.BR @\fIhost ,
meaning every address at
.IR host .
.TP 5
.I databytes
Maximum number of bytes allowed in a message,
or 0 for no limit.
Default: 0.
If a message exceeds this limit,
.B qmail-smtpd
returns a permanent error code to the client;
in contrast, if
the disk is full or
.B qmail-smtpd
hits a resource limit,
.B qmail-smtpd
returns a temporary error code.

.I databytes
counts bytes as stored on disk, not as transmitted through the network.
It does not count the
.B qmail-smtpd
Received line, the
.B qmail-queue
Received line, or the envelope.

If the environment variable
.B DATABYTES
is set, it overrides
.IR databytes .
.TP 5
.I localiphost
Replacement host name for local IP addresses.
Default:
.IR me ,
if that is supplied.
.B qmail-smtpd
is responsible for recognizing dotted-decimal addresses for the
current host.
When it sees a recipient address of the form
.IR box@[d.d.d.d] ,
where
.I d.d.d.d
is a local IP address,
it replaces
.IR [d.d.d.d]
with
.IR localiphost .
This is done before
.IR rcpthosts .
.TP 5
.I morercpthosts
Extra allowed RCPT domains.
If
.I rcpthosts
and
.I morercpthosts
both exist,
.I morercpthosts
is effectively appended to
.IR rcpthosts .

You must run
.B qmail-newmrh
whenever
.I morercpthosts
changes.

Rule of thumb for large sites:
Put your 50 most commonly used domains into
.IR rcpthosts ,
and the rest into
.IR morercpthosts .
.TP 5
.I rcpthosts
Allowed RCPT domains.
If
.I rcpthosts
is supplied,
.B qmail-smtpd
will reject
any envelope recipient address with a domain not listed in
.I rcpthosts
unless the sending host is a designated relay client (see the
description of the
.I relayhosts
file beow).

.I rcpthosts
may include wildcards:

.EX
   heaven.af.mil
   .heaven.af.mil
.EE

Envelope recipient addresses without @ signs are
always allowed through.
.TP 5
.I relayhosts
Allowed relay clients.  Each line is a host-suffix pair, separated by a
colon.  If the client's hostname matches one of the hostnames in the
file, that client is permitted to send mail to any host (i.e., to use us
as a relay), and the corresponding suffix is appended to all recipient
addresses generated by the client.

.I relayhosts
may include wildcards:

.EX
   heaven.af.mil:
   .heaven.af.mil:
   hell.irs.gov:.irs.virtdomain
.EE

For historical reasons, the
.B RELAYCLIENT
environment variable overrides this table.  If
.B RELAYCLIENT
is set, it has the same effect as there being a matching entry in the
.I relayhosts
file, using the value of
.B RELAYCLIENT
as the suffix.
.TP 5
.I smtpgreeting
SMTP greeting message.
Default:
.IR me ,
if that is supplied;
otherwise
.B qmail-smtpd
will refuse to run.
The first word of
.I smtpgreeting
should be the current host's name.
.TP 5
.I timeoutsmtpd
Number of seconds
.B qmail-smtpd
will wait for each new buffer of data from the remote SMTP client.
Default: 1200.
.SH "SEE ALSO"
tcp-env(1),
tcp-environ(5),
qmail-control(5),
qmail-inject(8),
qmail-newmrh(8),
qmail-queue(8),
qmail-remote(8)