The new Intelligent Message Filter version brought various improvements. This is triggering renewed interest. Some are considering it as their primary spam filter. Others are combining it with their current filtering technology in order to harden anti-spam protection.

IMF v2 is included with Exchange SP2. This service pack has been available for some months now. During this time, some common support problems have emerged. I will go through these issues today with the hope to smoothen IMF deployment at many organizations.

Here is an Index of the issues discussed:

1. Do Not Create the IMF AD Object Manually

2. Never Install IMF v1 on Top of SP2

3. Enabling IMF v2

4. Enabling IMF Online Updates

Do Not Create the IMF AD Object Manually

Whenever installing something as major as an Exchange Service Pack, reading the release notes is a must. Unfortunately a few lines in these notes are sometimes being misinterpreted causing some confusion. Here is the quotation from the release notes:

"Because Intelligent Message Filter is included in Exchange Server 2003 SP2, it is no longer an add-on and, therefore, a container must be created within Active Directory® directory service as follows:

Cn=UCE Content Filter,cn=Message Delivery,cn=Global Settings,cn=<ORG NAME>cn=Microsoft Exchange,cn=Services,cn=configuration,dc=<root domain>

You must have elevated rights to create this container - either Exchange Full Administrator or Exchange Administrator role at the organization level. The first time that you try to upgrade to a released or SP1 version of Exchange Server 2003, your permissions will be checked and a warning displayed if you do not have the correct rights level."

Some, on reading this, believe that they have to go and create the Active Directory object manually. In reality this is simply identifying the rights required during the service pack installation. The object itself is created by the service pack.

Thus to avoid problems, do not create the object manually. On running the SP installation, just make sure to have the necessary rights.

Never Install IMF v1 on Top of SP2

IMF v2 is included with Exchange SP2. This means that once the service pack is installed the filter is ready to be configured and enabled. On the other hand, the previous IMF version was a separate add-on install. Up to the date of writing, IMF v1 is still available for download from the Microsoft Download center.

The two versions are incompatible. For this reason SP2 requires IMF v1 to be uninstalled. The service pack installation automatically detects the presence of IMF v1 and prompts for this to be removed before proceeding.

Problems start if IMF v1 is installed on top of SP2. IMF v1 is unaware of SP2 and won't block such an installation. This corrupts IMF v2 and the filter won't work unless the correct setup is recovered. Resolving this problem requires un-installing IMF v1 and re-applying SP2.

Enabling IMF v2

On installing SP2, IMF v2 is disabled. This can be confusing especially to organizations that where previously running IMF v1.

First of all, contrary to what some would expect, the SP2 upgrade process does not retain the enablement status of IMF v1. SP2 will simply install IMF v2 in the disabled state independently of the previous IMF v1 configuration.

Secondly IMF v2 changes the interface through which it is enabled. In IMF v1 the Exchange System Manager used to be extended with a dedicated object located under:

<Organization> | Servers | <Exchange Server> | Protocols | SMTP | Intelligent Message Filtering

Through this object one could enable/disable IMF. As from SP2 this configuration object is not available any longer. Enablement was instead moved to the virtual server objects under the SMTP protocol:

1. Open the Exchange System Manager

2. Browse the left pane tree and open the properties for:
   <Organization> | Servers | <Exchange Server> | Protocols | SMTP | <SMTP Virtual Server>

   

3. From the General property sheet click on Advanced.

   

4. In the Advanced dialog that opens select the IP on which IMF is to be enabled and click on the Edit button.

   

5. Set the 'Apply Intelligent Message Filter' checkbox.

   

6. Save changes.

Enabling IMF Online Updates

Once you correctly install, configure, and enable IMF, you might think everything is in place. In reality there is still one important thing to do. Microsoft is now releasing regular updates to the IMF engine. These updates are being delivered though the standard Windows Update Service.

Nevertheless the updates won't be detected unless a little registry tweak is performed. Thus in order to keep up the system filtering effectiveness you should certainly make sure to plug into these updates. Follow this link for complete details on how to do this.