Mainteinance Complete!

November 24, 2007

We completed the network maintenance last night with zero downtime.

Here are some enhancements:

  • Added Server Memory: We doubled the amount of memory in the server for faster processing speed and delivery of mail.
  • Connections for Mail: We doubled the number of mail connections for enhanced spam filtering.
  • Spam Filtering: When someone sends an e-mail to you, it will go through a check as follows:
    • If the sender’s email server is listed in zen.spamhaus.org, or bl.spamcop.net (Realtime Blacklists of Spammers) it is rejected
    • If the sender’s email server doesn’t exist, meaning it is forged, then it is rejected
    • If the sender’s email address doesn’t exist, meaning it is spoofed, then it is rejected
    • If the sender of the mail is validated, then it is checked for viruses. If one is found, it is rejected
    • If it is clean, then the content is checked for Spam and assigned a score. If the score is greater than 20, it is rejected
    • If the score is less than 20, but greater than 5 it is passed to your local spam filter, SpamAssassin to see if the sender is in your “whitelist” which will allow it through. If it is not on the whitelist, then the subject will be rewritten to include ***SPAM*** and it will let the mail through
    • If the score is less than 5, then it will let the mail through (Note: you can change this score; see below)

    Once the mail makes it through, then you can set up local filtering. Here is an excellent tutorial to setup Junk filters and Filters in Microsoft. You can change the settings of your local SpamAssassin to automatically discard mail and/or reroute it to a Spam Box.

You can also change the score anywhere from 1 (most restrictive) to 19 (least restrictive). It is recommended that you leave the score to 5 for a week or so with the mail coming through. If you see mail tagged as Spam which should not be, this is called a false positive. If there are less than 5 senders caught, then whitelist them in SpamAssassin. If there are more than 5 senders then you might want to increase the score to 6 and leave it there for a week to see if that takes care of the false positives.

If you have questions about Spam Filtering, let me know in the comments and I’ll post the answers for everyone.

Posted by Chelle Yarbrough | Filed Under Uncategorized 

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