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)