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Exchange Message Filtering

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by dlweaver

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I'm running Exchage 5.5 on an NT 4 server. I've been getting bombarded with SPAM mail and in an attempt to relieve some of this "crap" from getting into my network, I chose to use the built in message Filtering feature of Exchange. I've entered the domains that the mail stems from in 2 fashions with alot of success but some domains are still getting in. One way I've listed the domain in the list is strictly by the domain name, i.e. domain.com, and I've also entered the domain using @domain.com,hoping that it would act somewhat like a wild card so anybody@domain.com would be unable to get to us. I don't know which one is supposed to be the correct way and like I said before, some domains are still able to get in. I've tried to do "WHOIS" queries for the troublesome domains and use the answer as the entry in the list and we're still getting pounded. Does anyone have any ideas other then purchasing 3rd party software to control the e-mail?

3 replies

by [_rick_>

@domain, name@domain and domain are all valid for this. For instance if you receve a message from @mail1.bogus.com and another from @mail2.bogus.com, instead of entering both full domain names you can add the common factor to the filter list - bogus.com, the connector should match it against both full domains.

If you want to restrict against a certain person then use the name@domain. If you want to restrict against a certain domain then use the @domain, but keep in mind the example - if you filter @mail1.bogus.com, messages from @mail2.bogus.com will still be permitted.

Also check your IMC routing to make sure that you are not inadvertently configured as a open relay. There are articles on this for Exchange 5.5, go to the technet WebSite and search on open relay.

As a thought you may want to consider investing in a content/spam filter for the IMC. These addon application range in price depending on what bells and whistles you want and need. On the low end with price (but notfunction) is an application found on http://www.nemx.com, it allows you to filter on address, subject, message content, Open Relay Database, and RFC header information. This app. ties directly in with the Exchange Directory and does not require a separate system. Maintenance is via the Exchange admin program.

This application does have some draw backs and the Exchange 5.5 version does have size limitations to the number of entries possible for each filter - which I understand is not true in the Exchange 2000 version. The size limitation is an inherited limitation of the Exchange 5.5 Directory Store - where the rules and filters are kept. Exchange 2000 uses Active Directory which has a much better capacity for data objects.

Good luck
-Rick

by dlweaver

Thanks for confirming the syntax for that filter list. I guess for me it's just a matter of not being able to keep up with all of them. I've got entries using all of the above mentioned formats and still am getting alot of SPAM. I'll be looking into purchasing a 3rd party package as soon as we get past the new year. Thanks for your help.

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