FidoSysop Blog

Blackholing Spam Notifications Prevents IP Blacklisting

How to prevent your server / hosting IP being blacklisted by spammers!

Your default inbox is probably full of spam without your knowledge!

When a spammer sends a blind email ([email protected]) to your domain the server sends a bounce notification to the reply to address in the spam email. That’s a major problem! Here’s how to fix it.

A client recently was getting bounce messages from AOL who blacklisted the sending IP address. To make a long story somewhat short. A spammer had used a forged mail from and reply to address of an AOL member. Then that member complained to AOL who blocked the mail servers IP.

If your using cPanel this is an easy fix. Login to your cPanel and select default address under the mail section. Click any thumbnail for a larger image opens in a fancybox.

cPanel Mail Section

This is the best way to handle unrouted email that’s sent to your domain.

Click the Default Address icon. Set any “unrouted” email to go into a blackhole. This prevents sending bounce notifications to the person that had their email address hijacked by spammers.

This will not effect normal routed email set up in your hosting account.

cpanel default email address settings

Are you running any cron jobs? Each time a crontab task is ran it sends a message to your default address. If you do not want this feature disable it. To do this navigate to your advanced cPanel section and click the Cron Jobs icon.

cPanel advanced settings section

By default you will see your system account name shown. Delete it and click submit. I already have it disabled here. This is what it looks like if you disabled cron email notifications.

cpanel crontab email settings

OK. So now we have your mail server configured not to send bounce notifications. And disabled crontab notifications. Lets clean out your default inbox.

cPanel defaults to your login name. I bet you have many thousands of garbage emails in there.

Under your cPanel mail settings area you will see a webmail icon. Click it.

cPanel will present a login to webmail screen that will open a new tab or window. Click the login to webmail link. Depending on how your webhost has webmail set up you might get a choice of mail clients to use. If you get a choice use Squirrel Mail. My server is defaulted to squirrel mail.

cPanel webmail login

When you first access SquirrelMail it will display a settings tab. Make any changes or just click update. If it goes back to the same tab put a few characters in the signature box. Your default inbox probably will look something like this.

Default email inbox full of spam.

Damn Spam! I had 39,000 spam messages eating up my disk space and most important, system resources!

You want to click the select all toggle then click the delete icon. Be sure to check bypass trash before clicking delete. Your default displayed messages probably defaults to 15 messages per page. If you have oodles of spam it will take forever to delete them all.

Best bet is to click the Options Link up top. You will then see a Display Preferences link. Click it. You will see the number of messages displayed toggle. If you are on shared hosting id go with 250 messages per page. You can fiddle with this setting but don’t overload the server.

Might want to run your domain through a blacklist test. Network-tools.com is one site that you can test your domain or IP address for blacklisting.

Another lesson i learned in the school of hard knocks.