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Block specific spamming addresses

How to block mail from known addresses or domains.


Block specific spamming addresses
Serdar Yegulalp

Spam, or unsolicited e-mail, is a chronic problem in organizations of all sizes, since it wastes server resources and becomes a headache for all involved. While there is no one foolproof method for stopping spam, there are several ways to cut down on its severity.

One of these involves setting Exchange to reject e-mail that matches specific domain and address criteria. Doing this requires that you edit the registry directly, so proceed with caution. Make sure you have a registry backup and can restore in case you mess up.


  1. Open REGEDT32 and navigate to the key

  2. Add a new String value (REG_SZ) in this key, with the value name TurfDir and the value C:Program FilesExchsrvrImcdataTurfdir. This is the directory where the "matched" messages are stored and is fairly arbitrary, but you will probably want to locate it within your Exchange Server folder hierarchy.

  3. Add another Multi-String (REG_MULTI_SZ) value: TurfTable. Each line in the Multi-String can contain one of two types of data: either a specific address to block (in the format, or a whole domain (in the format

  4. Restart the Internet Mail Connector.

Note that this technique will only work to block specific addresses or domains; it is not an intelligent mail filter. It is a good way to erect a basic line of defense against spammers from rogue domains, however. If this technique is particularly successful, you will want to purge the Turfdir directory periodically, or forward the matched messages to another spam-tracking authority.

In Exchange 5.0, this technique only works with specific addresses. In 5.5 and above, this technique will work either with specific addresses or whole domains.

Serdar Yegulalp is the editor of the Windows 2000 Power Users Newsletter.

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