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Exchange 2007 Anti Spam does a poor job of spam filtering

    Question

  • I am using Exchange Server 2007 SP1 in a Stand Alone Mode (all roles are on one server, only 50 users in company) and have enabled Anti Spam on the Hub Transport. I discontinued using Message Labs to filter email due to some issues and cost and was hoping the built in Exchange Anti Spam Filter used with ForeFront Security would be the answer.
    So far I have been somewhat dissapointed with the Anti Spam part. ForeFront does a great job of anti virus and attachment filtering but Spam making it to the users Inbox has increased tenfold after moving off of Message Labs and counting on the built in Anti Spam features of Exchange. And it is hitting a fairly high number of false positives. Its almost comical how many spams get thru and how many legitimate emails get sent to the users Junk Email Folder.

    Maybe I am missing something in my setup so here it is:
    - Enabled Anti Spam on the Hub Transport
    - Set Content Filters to: 9 delete, 8 Reject, 7 quarantine. Also set anything above 4 to go to users Junk Email Folder
    - Added the Spamhaus ZEN IP Block List: zen.spamhaus.org, tested and is working. I would also like to know of other Block Lists recommended.
    Additionally the majority of spam lately is coming from China IP's. I want to block ALL China, Korea, Russion IP's. Are there any blocklists that do ALL these IP's?

    - Enabled Sender ID and Sender Reputation

    - Enabled Anti Spam Updates and made sure it checks every hour. We us WSUS so I made sure it checks every hour for updates and auto approves all Exchange Anti Spam updates. Confirmed in Event Log that it does check and is installing updates every few hours.

    - Configured the Internet Transport to deny any email that tries to send as coming from our domain.

    Let me know if I am missing something or should I not try to rely on Exchange Anti Spam alone.

    Thanks,

    Monday, April 13, 2009 9:53 PM

Answers

  • Hi,

     

    I think that you need to adjust Content Filters setting to block more spam messages:

     

    I suggest you read following article:

     

    Adjusting the Spam Confidence Level Threshold

    http://technet.microsoft.com/en-us/library/aa995744.aspx

     

    Mike

    • Marked as answer by Mike Shen Friday, April 24, 2009 7:39 AM
    Wednesday, April 15, 2009 4:22 AM