PhpWiki - Home Page /2004-06-24

sendmail configuration

The problem

I have been noticing for a while that whenever my web server wants to send e-mail (some PHP applications send mail), it always appears to come from apache@localhost.localdomain. I never really bothered to look into this, until my Yahoo mail started filtering these messages as spam.

The headers of the message (before) were

Date:  Thu, 24 Jun 2004 08:33:55 -0400
From:  "root" <root@localhost.localdomain>  Add to Address Book
Message-Id:    <200406241233.i5OCXte05504@localhost.localdomain>
Content-Length:        13

What I really want is for the mail to come from apache@mpickering.homeip.net. I started researching how to do this, but kept running into dead ends until I found this link on sendmail's site. It reads, in part,

In some (fairly rare) cases, gethostbyname may fail to return the FQDN.

I guess gethostbyname is returning localhost.localdomain on my server; probably because I haven't configured it to know about its external DNS address.

My solution

Like many solutions given on my Wiki, I don't know if this is the "proper" method for making this work. It does work, though, which is the critical part for me.

I edited /etc/mail/sendmail.mc and added the following line to the bottom: define(`confDOMAIN_NAME', `mpickering.homeip.net')dnl

Then, I regenerated /etc/sendmail.cf (you should probably back it up first) by running

m4 /etc/mail/sendmail.mc > /etc/sendmail.cf

and finally, restarted sendmail with

/sbin/service sendmail restart

Now, when I send e-mail, the headers looks like this

X-Apparently-To:        mpicker0@yahoo.com via 66.163.170.248; Thu, 24 Jun 2004 08:09:11 -0700
X-Originating-IP:      [24.129.197.12]
Return-Path:   <root@mpickering.homeip.net>
Received:      from 24.129.197.12 (EHLO mpickering.homeip.net) (24.129.197.12) by mta101.mail.scd.yahoo.com with SMTP; Thu, 24 Jun 2004 08:09:11 -0700
Received:      (from root@localhost) by mpickering.homeip.net (8.11.6/8.11.6) id i5OF9Am06239 for mpicker0@yahoo.com; Thu, 24 Jun 2004 11:09:10 -0400
Date:  Thu, 24 Jun 2004 11:09:10 -0400
From:  "root" <root@mpickering.homeip.net>  Add to Address Book
Message-Id:    <200406241509.i5OF9Am06239@mpickering.homeip.net>
Content-Length:        13

Other sendmail debugging tools

In my searching, I found some good examples of setting up sendmail. Here's an old but good guide to setting it up, and testing it with telnet.

A quick way to send mail using sendmail is this: echo "Test message" | sendmail -v mpicker0@yahoo.com