December 25, 2012    



When working with SendMail for intranet environments, you may run into the following type of 553 5.1.8 error. This is an example from my own email system but with the domain name changed.


—– The following addresses had permanent fatal errors —–

<> (reason: 553 5.1.8 <>… Domain of sender address does not exist)

—– Transcript of session follows —–

… while talking to


<<< 553 5.1.8 <>… Domain of sender address does not exist 550 5.1.1 <>

User unknown <<< 503 5.0.0 Need RCPT (recipient)

Reporting-MTA: dns; Received-From-MTA: DNS;

localhost Arrival-Date: Tue, 25 Dec 2012 04:06:48 -0500

Final-Recipient: RFC822;

Action: failed Status: 5.1.8

Remote-MTA: DNS;

Diagnostic-Code: SMTP;

553 5.1.8 <>… Domain of sender address does not exist

Last-Attempt-Date: Tue, 25 Dec 2012 04:07:07 -0500

This type of error can occur when email is sent by cron jobs or other internal tasks running on hosts inside your network, and you have your own sendmail based email server. It happens because email sent from Linux hosts by cron jobs is sent as and the hostname is causing the email server to read it as a non-existent domain.

Adding these hostnames to your DNS does not resolve the problem.

You must add your own domain’s equivalent of the following lines to the /etc/mail/domaintable database file.


Then run make (with /etc/mail as the PWD) and restart sendmail.

That entry in the domaintable database converts all domain names that have the form to the true domain name of thus allowing sendmail to recognize the domain.