smtpfront(8) System Manager's Manual smtpfront(8)NAME
smtpfront - SMTP Front Ends
SYNOPSIS
smtpfront
DESCRIPTION
The code for SMTP is divided internally into two sections: front-end and back-end code. The front-end code handles the low-level details
of the protocol. The back-end code handles the validation and delivery details in a protocol-independant fashion.
FEATURES
The following features are common to all SMTP front-ends:
o Validates senders and recipients according to ``mailrules'' processing.
o If $RELAYCLIENT is set, all recipient addresses not rejected by mail rules are allowed, and its contents are appended to each recipient
address. Back-end validation is omitted.
o Handles RFC 2554 SMTP authentication. After authentication all recipients not rejected by mail rules are allowed, and back-end valida-
tion is omitted.
o Automatically handles either bare NL or RFC 821/2821 compliant CR/NL end-of-line conventions.
o Rejects messages that exceed $DATABYTES bytes in the body.
o Times out connections after $TIMEOUT seconds of inactivity (defaults to 1200 seconds or 20 minutes), or $SESSION_TIMEOUT seconds after
the connection was established (defaults to 86400 seconds or 24 hours).
o Counts the number of "Received:" and "Delivered-To:" headers, and rejects the message if more than $MAXHOPS of either are seen (defaults
to 100).
o All error responses are logged.
o Handles (ignores) RFC 1869 extended parameters on the ``RCPT TO:'' and ``MAIL FROM:'' commands.
o Initial greeting message is configureable by $SMTPGREETING.
o Rejects bounce messages (messages with an empty envelope sender) that attempt to deliver to multiple recipients.
o Optionally adds a fixup "Received:" header for hosts that have different incoming and outgoing hostnames or IPs. Set
$FIXUP_RECEIVED_HOST and $FIXUP_RECEIVED_IP if you want this header added.
BACK ENDS
smtpfront-echo
Uses the echo backend to simply echo back the sender and recipient parameters, and the size of the data to the client.
smtpfront-qmail
Uses the ``qmail validation features'' to validate addresses, and the ``qmail backend'' to deliver messages.
smtpfront-reject
If $SMTPREJECT is set, all SMTP commands are rejected with this message. If the message starts with a "-", a permanent error number
is used and the leading "-" is stripped. If $SMTPREJECT is not set, it execs its command line.
SEE ALSO pop3front(8)
/usr/share/doc/mailfront/html/mailrules.html
/usr/share/doc/mailfront/html/qmail-validate.html
/usr/share/doc/mailfront/html/qmail-backend.html
http://untroubled.org/mailfront/
smtpfront(8)
Check Out this Related Man Page
qmail-smtpd(8) System Manager's Manual qmail-smtpd(8)NAME
qmail-smtpd - receive mail via SMTP
SYNOPSIS
qmail-smtpd
DESCRIPTION
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 tem-
porary 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 exam-
ples,
VERIFY="192.168.1.1"
VERIFY=":10101"
VERIFY="DEFER,:10101"
VERIFY="DEFER,192.168.1.1:10101"
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.
SEE ALSO tcp-env(1), tcp-environ(5), qmail-control(5), qmail-inject(8), qmail-newmrh(8), qmail-queue(8), qmail-remote(8), qmail-verify(8)qmail-smtpd(8)