Mail delivery: DNS: Service unavailable error

Posted on in Categories , , , , , , , , , , , , , last updated December 4, 2008

Q. My mail delivery fails with DNS: Service unavailable error. How do I fix this error under Linux / UNIX operating systems?

A. This error indicate that your DNS name resolution is not working correctly. Make sure dns client configuration is correct and your dns servers (or ISPs DNS servers) are working.

Also make sure the remote mail server receiving the mail from the local server is unable to resolve the local mail servers hostname. The local mail server needs to have a valid working fully qualified domain name (FQDN).

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.