Tuesday, November 30, 2010

Configuring Sendmail RedHat /CentOS/Fedora

Configuring it is very simple. First you'll need the sendmail-cf package. Install it using yum:
[root@mail-server ~]# yum install sendmail-cf
Edit the file /etc/mail/sendmail.mc and add the following lines. Make sure you set your mail server domain name where it's bolded:
MASQUERADE_AS(yourdomain.com)dnl
MASQUERADE_DOMAIN(yourdomain.com)dnl
In the same file /etc/mail/sendmail.mc remove the "dnl" from the beginning of the lines so it will look like this:
LOCAL_DOMAIN(`localhost.localdomain')dnl
FEATURE(masquerade_envelope)dnl
FEATURE(masquerade_entire_domain)dnl
Save the file and compile it using m4:
[root@mail-server ~]# m4 /etc/mail/sendmail.mc > /etc/sendmail.cf
Send Sendmail a -HUP signal using kill or simply restart the daemon for the configuration changes to take effect:
[root@mail-server ~]# service sendmail restart

Testing your configuration using sendmail

And that's it! you're done. Just send yourself a test email to make sure it is really working:
[root@mail-server ~]# /usr/sbin/sendmail -t < mail.txt
Where the contents of the mail.txt file are:
Date: Wed Dec 1 08:41:54 2010
To: you@somewhere.com
Subject: The subject of the message
From: whatever@somewhere.com
Body of message goes here

Testing your configuration using mutt

You can also use mutt to test, which is a bit simpler (and you can also add the -a parameter for file attachment):
[root@mail-server ~]# mutt -s "Test Email" you@somewhere.com < /dev/null

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