Recently one of our reseller Cpanel clients on one of our shared servers managed to have the shared server IP blacklisted in two popular blacklists by sending out spam email using an automated mailing script. As you may know, when one client gets a shared IP blacklisted all clients on that IP are then effected so this was a priority case for us.

Believe it or not many of the most popular blacklists such as SpamCOP are more than happy to remove an IP as a spam source providing you can prove you are not a spam trader. Some of the blacklists you must manually request an IP to be removed however others will automatically remove an IP if it does not get any complaints or trap any spam from it within a number of hours.

Tips to Recover from your Shared Cpanel Server Blacklisting

1. Of course the first step was to remove the offending auto mailing script and shutdown the said client's hosting account. Done.
2. Next, search the blacklists for your shared IP. There are some good free tools out there to help you with this. Such as MX Toolbox.
3. Contact each blacklist your IP appears in and advise you have taken steps to remove your offending client and increase mail security. Await further instruction from each blacklist.

On Spam Prevention using WHM
As the shared IP in question here belonged to a WHM server we run, we will cover some WHM settings that could go a long way in the fight against clients who like to spam.

Load up WHM as root and click through to Main >> Server Configuration >> Tweak Settings and scroll down to mail. There are two very useful settings here.

The maximum each domain can send out per hour

This is quite self explanatory, set it to a low number rather than the default of 0 which is unlimited and each domain is seriously halted when it comes to sending bulk mails.

Prevent the user "nobody" from sending out mail to remote addresses

Some poorer auto mailing scripts will send mail out as the user nobody, set this setting to enabled and this decreases the risk too.

We hope these notes can be of use to individuals and companies alike in the ongoing fight against spam.