Outlook Exceptions

The Rules cache wasn't made to be broken. A better way to create e-mail filters will come with Outlook 2003.

• By Bill Boswell
• August 26, 2003

Bill: As people in my office start to build junk e-mail filters, they worry about vendors who might get knocked down. So, users have a tendency to add every known e-mail to their exception list.

Many are now getting some message that their e-mail is running out of space. I am sure it is because of an Outlook limitation but can you tell me what the largest number of addresses can be in the exception list? I've searched Technet but have been unable to find the answer.

I would almost like to build a server side list of all of our known contacts and any e-mail not on the list gets knocked down. I'm assuming that would be too large.
— John Eldred

John, Outlook has a 32K limit on the size of the Rules cache. This is an architectural limitation and cannot be overridden with a Registry hack. Outlook 2003, now in beta, has the same limit, but the spam-handling features are a bit more sophisticated so you might be able to tune your spam blocking to stay under the limit.

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As for doing all this work on the server side, I have good news for you if you're willing to upgrade. Exchange 2003 has lots of great anti-spam features, including the ability to build server-side filters. The filters can block incoming messages from open relays and known spam addresses by downloading lists from a Real-time Blacklist (RBL) vendor. You can also configure the list to exclude or include e-mails based on SMTP domain or sender's IP address.

Hope this helps.