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I’ve explain how you can wind up on a SPAM blacklist in a previous blog. I’ve also explain how to get off once you get on… here I’ll try to focus on being proactive about avoiding this situation.

If you own your own Exchange or email server; the most effective way to stop getting on SPAM blacklist is to use a paid third party vendor such as Postini or GFI MailEssentials Online to be act as your SMTP or outgoing email service. Let’s call this for short using a proxy SMTP service. What a proxy SMTP service can do is basically protect you from yourself. Meaning any negligence that you do, the outgoing filter system will try to compensate irregular email usage. For example if mass emails worm infects an unsuspected computer on your network, a good online filter will let you know of the situation and stop the flow. Also this separation of outgoing emails will force all emails to flow out of the proxy SMTP service, which will eliminate the possibility of your IP getting blacklisted. It delegates the blacklisting issues to them and can give you a piece of mind.

If you are not interested in a paid service you can just take some other simple measures to prevent getting blacklisted.

  1. One is to not send out emails with more than a few recipients. If you do need to send out a notification of mass proportions, use a 3rd party system like Vertical Market or Constant Contact to do it.
  2. Keep your computers well protected. Inform your users to let you know of any oddities and make sure you have virus protection on all workstations.
  3. Setup a firewall rule that blocks outgoing port 25 except for the email server. What this means is even if a workstation gets infected with a mass mailing worm virus, the firewall will block all outgoing emails. It will not fix the fundamental issue, but it will prevent you from getting blacklisted.
  4. Make sure your Exchange Server is well protected. Make sure your passwords for all users are hard to guess. Also make sure your Exchange is setup properly so it will not “relay” emails. Lastly do not use your server as a browsing machine. If you need to research or do any sort of extensive browsing – avoid doing it on the server.
  5. Monitor your Exchange queue – make sure you check into it every few weeks, just to make sure it has not ballooned out of control with some issue.

Getting proactive is a great way of preventing a painful situation. There is nothing fun about your emails getting bounced back and it takes time, effort and money to clear things up again. An ounce of prevention will save you a pound of pain.