Using Sendmail as a Mail User Agent (MUA)

Computer History Notes - Herong's Tutorial Notes

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

∟Using Sendmail as a Mail User Agent (MUA)

This section provides an example using Sendmail a Mail User Agent (MUA) to transfer a local email message.

Sendmail is designed as a Mail Transfer Agent (MTA), not a Mail User Agent (MUA). There are other better MUA programs available on UNIX systems, like mail, elm, and pine.

But Sendmail can be used as MUA to collect an email message directly from the user interface and transfer it to the machine identified in the recipient email address. Here is an example session of using Sendmail as a MUA to transfer a local email on a Linux system:

$su root

#which sendmail
/usr/sbin/sendmail

#ls -l /var/spool/mail/herong
-rw-rw----   1 herong   mail   442638 Jul 20 12:08 herong

#rm /var/log/mail.log
#rm /var/spool/mail/herong
#sendmail -X /var/log/mail.log -v herong
From: root
To: herong
Subject: First Test

Hi. This is a test.
.
herong... Connecting to local...
herong... Sent

#more /var/log/mail.log
<<< From: root
<<< To: herong
<<< Subject: First Test
<<<
<<< Hi. This is a test.
<<< .
>>> herong... Connecting to local...
=== EXEC procmail -a -d herong
>>> From root@darkstar.home.com Thu 23 Jul 12:25:29 1998
>>> Return-Path: <root>
>>> Received: (from root@localhost)
>>>       by darkstar.home.com (8.9.0/8.9.0) id MAA00402
>>>       for herong; Thu, 23 Jul 1998 12:25:29
>>> Date: Thu, 23 Jul 1998 12:25:29
>>> Message-Id: <199807231625.MAA00402@darkstar.home.com
>>> From: root@darkstar.home.com
>>> To: herong@darkstar.home.com
>>> Subject: First Test
>>>
>>> Hi. Test is test 1.
>>> herong... Sent

#more /var/spool/mail/herong
From root@darkstar.home.com Thu 23 Jul 12:25:29 1998
Return-Path: <root>
Received: (from root@localhost)
      by darkstar.home.com (8.9.0/8.9.0) id MAA00402
      for herong; Thu, 23 Jul 1998 12:25:29
Date: Thu, 23 Jul 1998 12:25:29
Message-Id: <199807231625.MAA00402@darkstar.home.com>
From: root@darkstar.home.com
To: herong@darkstar.home.com
Subject: First Test
Status: O

Hi. Test is test 1.

Notice that:

darkstar.home.com is a temporary host name of the local Linux machine.
"-X" and "-v" options help us how Sendmail works on an email message for a local email address.
On a Linux system, the email box of user "herong" is located at /var/spool/mail/herong.