Here at Northwest Nexus, we use various  Real-time Black hole Lists (RBL) in the fight against SPAM.   These lists are served via DNS and contain IPs of known spamming hosts or Open Relays.   If you have an Open Relay Email Server you may end up on these lists that we use,  then your Email Server will no longer be able to send mail to our network or any network that we deliver Email to.

If your system is an Open Relay and is being used for spam, you need to do the following steps to secure your system and get your machine off of the RBL lists.
 

1. Test your system.   This can be done by running the following telnet command from your mailhost...
telnet relay-test.mail-abuse.org

This will start a set of Relay tests against your machine.   If you pass, the following will be printed out at the end of the diagnostics you see at your telnet session screen...

"System appeared to reject Relay attempts"

A sample of what this test looks like can be found here.

Another way to test your system is to go to ORDB.ORG and request a remote test. Be aware though that if your host fails this test and is found to be an open relay, your IP will be added to the ORDB RBL list.

If your system passes, than go on to step 3 to remove your IP from the RBL lists.  If your system fails, then do step 2 before step 3.
 

2. This step will give you information on how to secure your Email Server from 3rd party Email Relaying.  Information and instruction pointers for most all MTA (Mail Transport Agents) can be found at   Mail-Abuse.org .   Find the Email system you use and follow the link to get instructions on how to secure your Email Server.    Once fixed, you should once again run the test described in step 1.
   
   
3. Once you've corrected the Open Relay issue, you can now search the various RBL lists to see if your Email Servers IP has been added.   The easiest place to do this from is from DNSSTUFF.COM  RBL database checker (Use the "Spam Database Lookup" box).   This site will query all known RBL sites for a given IP and report back whether that IP is listed or not.   Note that this site can be slow at times.
   

If your IP is listed, it will be shown in the box for the listed RBL site.   You should then follow the links to the site in question where you will find instructions for removal from that sites database.   Most have a simple web form to fill out while some others require you to send an emal.