Using Sendmail as a STMP Server Daemon

Computer History Notes - Herong's Tutorial Notes

∟1983 - "Sendmail" Mail Transfer Agent Developed by Eric Allman

∟Using Sendmail as a STMP Server Daemon

This section provides an example using Sendmail as a daemon acting as a STMP server to receive email messages from remote machines.

Sendmail can be used a daemon to:

Listen on the default port 25 for any incoming SMTP connections to receive email messages.
Process email messages delayed in the mail queue periodically.

Here is an example session of using Sendmail as a daemon to receive incoming new emails and process old emails in the queue.

(On darkstar machine)
%su
#ps -x | grep sendmail
250  ?  S   0:00 sendmail: accepting connections on port 25
#kill 250

#rm /var/log/mail.log
#rm /var/spool/mqueue/*
#rm /var/spool/mail/*
#sendmail -bd -q20m -X /var/log/mail.log
#ps -x | grep sendmail
323  ?  S   0:00 sendmail: accepting connections on port 25
#


(Go to another machine and login as herong)
$telnet darkstar.home.com 25
Trying 192.168.0.2
Connected to darkstar.home.com.
Escape character is '^]'.
220 darkstar.home.com ESMTP Sendmail 8.9.0/8.9.0 ready; Thu, 13 ...
HELO localhost.home.com
250 darkstar.home.com Hello localhost [192.168.0.1], pleased to mee...
MAIL From: herong@localhost.home.com
250 herong@localhost.home.com... Sender ok
RCPT To: root@darkstar.home.com
250 root@darkstar.home.com... Recipient ok
DATA
354 Enter mail, end with "." on a line by itself
From: herong@localhost.home.com
To: root@darkstar.home.com
Subject: Third Test

Hi. Third Test
.
250 VAA00143 Message accepted for delivery


(Back on darkstar machine)
#more /var/log/mail.log
00142 >>> 220 darkstar.home.com ESMTP Sendmail 8.9.0/8.9.0 ready; ...
00142 <<< HELO localhost.home.com
00142 >>> 250 darkstar.home.com Hello localhost [192.168.0.1], ple...
00143 <<< MAIL From: herong@localhost.home.com
00143 >>> 250 herong@localhost.home.com... Sender ok
00143 <<< RCPT To: root@darkstar.home.com
00143 >>> 250 root@darkstar.home.com... Recipient ok
00143 <<< DATA
00143 >>> 354 Enter mail, end with "." on a line by itself
00143 <<< Subject: Third Test
00143 <<<
00143 <<< Hi. Third Test
00143 <<< .
250 VAA00143 Message accepted for delivery

#more /var/spool/mail/root
From herong@darkstar.home.com Thu 23 Jul 12:25:29 1998
Return-Path: <herong@darkstar.home.com>
Received: from localhost.home.com (localhost [192.168.0.1])
      by darkstar.home.com (8.9.0/8.9.0) id VAA00143
      for root@darkstar.home.com; Thu, 23 Jul 1998 12:25:29
Date: Thu, 23 Jul 1998 12:25:29
Message-Id: <199807230114.VAA00143@darkstar.home.com>
From: herong@localhost.home.com
To: root@darkstar.home.com
Subject: Third Test

Hi. Third Test