Exchange 2003: Unable to add to the server Junk E-mail Lists

If you're using Exchange 2003, and have users who make use of their junk e-mail lists, then this post may come in handy.

Exchange has a limit of 512 KB for your junk e-mail lists. This is a cumulative total for all of your lists, safe senders, blocked senders, etc.

I ran into this problem and had a heck of a time finding the solution for it. The exact error message is pretty scarce on the internet, and even scarcer on the Microsoft Web Sites.

The workaround is outlined in Microsoft KB Article 842510.

Open Regedit

Navigate to:

HKLM\System\CurrentControlSet\Services\MSExchangeIS\ParametersSystem

Locate the  Dword Key "Max Extended Rule Size" (without the quotes, but with the spaces). If the key doesn't exist, create it.

The value, in decimal, represents the number of bytes that you want to use. If you want to increase the limit to 1 MB, change it to 1024.

As far as I can tell, you don't have to restart anything, except possibly outlook on the client's machine.