Deploying Junk Mail Filter Lists in Outlook 2003

Microsoft continues to roll out a steady stream of post-Service Pack 1 (SP1) hotfixes for Outlook 2003--nearly two dozen so far by my count. (To find them all, search the Microsoft Knowledge Base for: Outlook kboffice2003presp2fix.) One hotfix released late last month caught my eye because it deals with importing junk mail filter lists into Outlook 2003. This feature lets you use registry values to tell Outlook to import the Safe Senders, Safe Recipients, and Blocked Senders lists from specific locations and either overwrite the user's existing junk mail filter lists or append entries to them.

The junk mail filter lists that Outlook imports are just text files with an email address or domain name on each line. For example, you might want to include on the Safe Senders list the domain names of all the key partners that your organization deals with regularly. An easy way to prepare these lists for import is to use Tools, Options, Junk E-mail to display the Junk E-mail Options dialog box, build the lists there, then click Export to File to create each text file.

Typically, you deploy the junk mail filter list files along with the necessary registry values when you deploy Office or Outlook with the Custom Installation Wizard (CIW) from the Microsoft Office 2003 Resource Kit. Set the import options on Screen 10, under Microsoft Office Outlook 2003, Tools, Options, Preferences, Junk E-mail. Use screen 11 to add the files to the installation. You can also place the files on a network volume instead of deploying them to the local client machine.

After installation, you might want to deploy a refresher for the junk mail filter lists when your company signs a big new client, to make sure that Outlook doesn't mark mail from that client's staff as junk mail. The Custom Maintenance Wizard (CMW) has settings similar to those in the CIW. By default, the import appends to the user's existing junk mail filter lists. The user can modify any junk filter list you import by adding, modifying, and deleting entries.

Here's how the import feature works: Setting the Junk Mail Import List option in the CIW or CMW to import the junk mail lists will set a DWORD value named JunkMailImportLists in the HKEY_CURRENT_USERSoftwareMicrosoftOffice11.0OutlookOptionsMail lists registry subkey to 1, creating that value if it doesn't already exist. When Outlook sees that JunkMailImportLists has a value of 1, it imports the lists from the locations given in the other registry values that the CIW or CMW settings control, then changes the value of JunkMailImportLists to 0.

You can also use Group Policy Objects (GPOs) to manage the settings for the locations of the junk mail filter lists and whether Outlook appends or overwrites the lists. The Outlk11.adm administrative template file doesn't contain a setting for deploying the JunkMailImportLists value as a policy setting--that setting is in the HKEY_CURRENT_USERPoliciesSoftwareMicrosoftOffice11.0OutlookOptionsMail subkey. At first, this might seem to be a curious omission. If you can use policy settings to set the junk filter list locations, why not use a policy setting to turn on the import as well? If you try to deploy JunkMailImportLists as a policy setting, you'll run into performance problems. Outlook can't reset the JunkMailImportLists value from 1 to 0 after it performs the import if JunkMailImportLists is a policy setting. As a result, Outlook periodically checks the value of JunkMailImportLists, sees that the value is still 1, and performs the import again and again and again, causing excessive remote procedure call (RPC) traffic as Outlook updates the user's junk mail filters, which are actually stored in the Exchange mailbox.

What caught my eye about the January 25, 2005, hotfix and the changes detailed in the Microsoft article "The JunkMailImportLists registry value may cause poor performance in Outlook 2003" at http://support.microsoft.com/?kbid=893057 is that the hotfix makes two changes in the behavior I've just described. Chances are that you don't need and won't want to install this hotfix, but because it will probably be part of SP2, you should be aware of these changes.

The changes address both how Outlook handles the JunkMailImportLists registry value and when it performs the import. With the hotfix applied, Outlook no longer resets the value of JunkMailImportLists to 0 after it performs an import. Outlook also won't look at the value of JunkMailImportLists repeatedly. Instead, it will perform the import only once per Outlook session, which eliminates the performance problems surrounding repeated imports of the junk mail filter lists.

The hotfix's change in behavior potentially raises two new problems, however. If JunkMailImportLists remains set to 1 after an import, so that the import takes place each time Outlook starts, you almost certainly will want to have the import append to the user's junk mail lists, not overwrite them. This behavior is the default, so you probably will never need to worry about it, but you still might want to check the setting for Overwrite or Append Junk Mail Import List in the CIW, CMW, or Group Policy editor, just the same.

What if you really do want to import the list only once? Because Outlook with the hotfix applied won't reset JunkMailImportLists to 0 after import, you'll need to do that through some other means. Alternatively, you could delete the import files or delete or blank out the registry values that hold the locations of the import files. You can use the CMW, a logon script, or even a GPO to make these changes. The problem is that you really have no way of knowing when the import has occurred and thus when to turn off the import settings. You'll just have to guess. A good strategy, therefore, might be to leave the junk mail lists themselves in place, just in case the user missed the opportunity for an automated import. The user can always import them manually by using Outlook's Junk E-mail Options dialog box.

So who needs to apply this hotfix? I can think of only one scenario in which it would be necessary, given that you already have a complete mechanism for setting up the import of junk file lists in the CMW or, if you didn't do an enterprise installation of Outlook, through a logon script that configures the necessary user preference settings in the registry. That scenario would be where you want to mandate, through GPOs, that Outlook import the junk mail filter lists each and every time Outlook starts. Keep in mind, however, that you can mandate only the import process. Even if you use a policy setting to overwrite the user's existing junk mail filter lists, the user can still edit those lists during their Outlook sessions and reverse your changes.