The arrival of regular updates for the Exchange Intelligent Message Filter was announced some time ago. The first of these is now available, ready for download!
The schedule for these updates is fixed to twice per month. On the first and third week of each month a new update will be made available. In this type of filter, keeping the engine up-to-date with the latest spamming trends is what makes all the difference. Thus, this is expected to dramatically improve IMF's filtering effectiveness.
These updates are for IMF v2 which ships with Exchange SP2. Thus the first step is to make sure this is installed. If you are unsure, just open the Exchange server properties from the System Manager. On the General Page the text "Service Pack 2" should be shown.
The updates are available via Microsoft Update. Nevertheless, before tapping into them, you will need to perform a registry tweak:
Open the registry editor: Run > regedit.exe
Browse to: HKLM\SOFTWARE\Microsoft\Exchange
Create a new DWORD value named ContentFilterState
Set its value to 1
This change is necessary since otherwise the updates won't be detected. To avoid having to remember the registry tweak, I prepared a little script that will create this value automatically. Follow the article download links to get the script, save it to the Exchange server machine, and open it from Windows Explorer. This will automatically import the new value.
Once done, you will be ready to grab a copy of the IMF updates through Microsoft Update. The update will only require restarting the IIS Admin service and can be uninstalled through Add/Remove programs.
Alexander Nikolayev published more details on this update at the Exchange Blog (see references). So make sure to check this out.
References
Alexander Nikolayev's - Intelligent Message Filter Updates
How to update the Intelligent Message Filter version 2 in Exchange Server 2003 SP2