You can use any of the following services to see if your IP address (s) have been blocked,
* The Abusive Hosts Blocking List
* SpamCop Blocking List
* Spamhaus Block List (SBL)
* Composite Blocking List (CBL)
* Weighted Private Block List (WPBL)
I am wondering if my server is being used to send out or relay spam. How can I check?
You can test your Mail server to see if it's running an open relay by using Netowrk ABUSE clearinghouse system. Point your browser at: http://www.abuse.net/relay.html
My Mail server was reported as an open relay. Is this true?
Pertaining to the Exim mail server for the cPanel/WHM and DirectAdmin
By default, the Exim mail server shipped with the cPanel/WHM and DirectAdmin is NOT open relay.
Now, if you are using a default address to "catchall" all the invalid and un-routed email messages to your domain, some of the "open relay" testing services will report that your domain is an open relay. But this is NOT true and your Mail server is NOT an open relay. The "open relay" report of these services is flawed in that context.
We highly recommend that you DISABLE the default address and do NOT use catchall.
If you are not sure that your server is secure, we suggest you sign up for the ServerTune Plan.