Fighting Spam on cPanel Servers

On cPanel servers there are a several different tools that are built into cPanel that can be used to help control the flow of spam both in and out of your server.

Spam Assassin


The simplest one is Spam Assassin that is available and configurable on a per site basis on cPanel servers.  Within the cPanel interface for each domain on a server Spam Assassin can be enabled and configured on a per domain basis. The configuration options available are to set a spam score to remove mail, whitelist email addresses, and blacklist email domains.


Please be advised that Spam Assassin will consantly be learning what is spam and what is not on your server.  And the more mail is processed on your server, the quicker Spam Assassin will lean what is spam and what is not.


RBL  – Remote Blacklists


One serverwide setting that can be extremely effective at stemming the tide of inbound spam messages to your server is to enable RBLs.  What these lists do is check each of the IPs that is attempting to send mail to your server against a remote list of known spammers. These remote lists are maintained by a large community of system and mail admistrators, and are one of the most effective tools available at fighting the flow of spam into your server.

On cPanel servers enabling RBLs is a simple matter.

WHM Exim Config Link

  • Log into WHM for your server, and use the find field to search for ‘exim
  • One of the links that this will display is ‘Exim Configuration Editor
  • Go ahead and click on this link
  • Scroll down to the RBL section
  • Put a check in both ‘RBL: bl.spamcop.net‘ and ‘RBL: zen.spamhaus.org’
  • Click save at the bottom of the page


Now your server is configured to filter all incoming mail against these two RBL lists.


WHM Exim RBLs


Controlling Outgoing Mail From Your Server


Within WHM there are some settings that can limit the number of email such as number of messages sent per hour,  and sender verifcation.


Limiting Messages Sent Per Hour

  • Log into WHM for your server, and use the find field to search for ‘tweak settings’
  • Click on Tweak Settings
  • Scroll down to the Mail section
  • If you wish to limit the number of messages sent per domain per hour just set the value you want in box next to ‘The maximum eachdomain can send out per hour (0 is unlimited)’


WHM Limit SMTP


Enabling Sender Verification

  • Log into WHM for your server, and use the find field to search for ‘exim
  • One of the links that this will display is ‘Exim Configuration Editor
  • Go ahead and click on this link
  • Scroll down to the Mail section
  • Put a check next to Sender Verification and then click save at the bottom of the page


WHM Sender Verification


While tweaking the available settings can help control the flow of outgoing mail, your system admistrator still will need to remain vilagant to ensure your server is not sending out spam.

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