Posted by Steve on Mon 8 Nov 2004 at 09:41
Open relays allow people to use your mail server to deliver spam and mail to people whilst using your resources.
None of the mail servers which are part of the Debian operating system are setup insecurely by default, but if you are new to setting up a mail server you should be cautious that you do not open your server accidently.
One very simple way of testing it is to fire off an automated test.
From your mail server run:
telnet relay-test.mail-abuse.org
This will attempt to connect back to your machine and run a series of mail relaying tests against it.
The success or failure will be printed at the end of the run.
If you are inadvertantly running as a relay consult your mail server documentation for tips on how to prevent it.
This article can be found online at the Debian Administration website at the following bookmarkable URL (along with associated comments):
This article is copyright 2004 Steve - please ask for permission to republish or translate.