qmail-smtpd
receives mail messages via the Simple Mail Transfer Protocol (SMTP)
and invokes
qmail-queue
to deposit them into the outgoing queue.
qmail-smtpd
must be supplied several environment variables;
see
tcp-environ(5).
qmail-smtpd
is responsible for counting hops.
It rejects any message with 100 or more
Received
or
Delivered-To
header fields.
qmail-smtpd
supports ESMTP, including the 8BITMIME and PIPELINING options.
TRANSPARENCY
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
http://pobox.com/~djb/docs/smtplf.html.
qmail-smtpd
accepts messages that contain long lines or non-ASCII characters,
even though such messages violate the SMTP protocol.
CONTROL FILES
badmailfrom
Unacceptable envelope sender addresses.
qmail-smtpd
will reject every recipient address for a message
if the envelope sender address is listed in
badmailfrom.
A line in
badmailfrom
may be of the form
@host,
meaning every address at
host.
databytes
Maximum number of bytes allowed in a message,
or 0 for no limit.
Default: 0.
If a message exceeds this limit,
qmail-smtpd
returns a permanent error code to the client;
in contrast, if
the disk is full or
qmail-smtpd
hits a resource limit,
qmail-smtpd
returns a temporary error code.
databytes
counts bytes as stored on disk, not as transmitted through the network.
It does not count the
qmail-smtpd
Received line, the
qmail-queue
Received line, or the envelope.
If the environment variable
DATABYTES
is set, it overrides
databytes.
localiphost
Replacement host name for local IP addresses.
Default:
me,
if that is supplied.
qmail-smtpd
is responsible for recognizing dotted-decimal addresses for the
current host.
When it sees a recipient address of the form
box@[d.d.d.d],
where
d.d.d.d
is a local IP address,
it replaces
[d.d.d.d]
with
localiphost.
This is done before
rcpthosts.
morercpthosts
Extra allowed RCPT domains.
If
rcpthosts
and
morercpthosts
both exist,
morercpthosts
is effectively appended to
rcpthosts.
You must run
qmail-newmrh
whenever
morercpthosts
changes.
Rule of thumb for large sites:
Put your 50 most commonly used domains into
rcpthosts,
and the rest into
morercpthosts.
rcpthosts
Allowed RCPT domains.
If
rcpthosts
is supplied,
qmail-smtpd
will reject
any envelope recipient address with a domain not listed in
rcpthosts.
Exception:
If the environment variable
RELAYCLIENT
is set,
qmail-smtpd
will ignore
rcpthosts,
and will append the value of
RELAYCLIENT
to each incoming recipient address.
rcpthosts
may include wildcards:
heaven.af.mil
.heaven.af.mil
Envelope recipient addresses without @ signs are
always allowed through.
smtpgreeting
SMTP greeting message.
Default:
me,
if that is supplied;
otherwise
qmail-smtpd
will refuse to run.
The first word of
smtpgreeting
should be the current host's name.
timeoutsmtpd
Number of seconds
qmail-smtpd
will wait for each new buffer of data from the remote SMTP client.
Default: 1200.
RECIPIENT VERIFICATION
Recipient verification is enabled with the
VERIFY
environment variable. This can be used to specify per-recipient
rejection of invalid recipient addresses (immediate verification
causing a permanent 550 error response to the RCPT command),
or deferred rejection at DATA time (554 response) of the whole
session if any recipient addresses don't exist.
To verify an address,
qmail-smtpd
uses a separate
qmail-verify
UDP server. By default this will be on the loopback address 127.0.0.1,
port 11113. Enable verification like this,
VERIFY=":"
VERIFY="DEFER"
(for immediate, deferred verification respectively). A different IP
address and/or port can be specified for
qmail-verify
as in these examples,
Recipient verification may be explicitly disabled by setting
VERIFY
to an empty string,
VERIFY=""
Addresses with domains appearing in
control/rcpthosts
but not in
control/locals
or
control/virtualdomains
will be considered valid, reflecting qmail's standard behaviour.
Note that if the environment variable
RELAYCLIENT
is set, no checking is carried out.
qmail-verify
needs to be running to respond to recipient
verification queries. If no
qmail-verify
response is received a temporary 451 error response is
given to the remote system and the session terminated.