This post originated from an RSS feed registered with .NET Buzz by Doug Thews. Original Post: Changing Outlook Attachment Behaviors Feed Title: IlluminatiLand Feed URL: http://apps5.oingo.com/apps/domainpark/domainpark.cgi?client=netw8744&s=JETBRAINS.COM Feed Description: A technology blog for people enlightened enough to think for themselves Latest .NET Buzz Posts Latest .NET Buzz Posts by Doug Thews Latest Posts From IlluminatiLand

As promised, here's how you can change the behaviors for Outlook attachment blocking (at the client level - this does not include blocking at the e-mail server gateway). This applies only to users of Outlook 2000 and Outlook XP - with the latest service packs installed.

You can add or remove attachment file types to block by adding the following registry string values. If you are in a Microsoft Exchange environment and your administrator has configured the Outlook Security settings, ask the administrator to modify the security settings for your mailbox, they will override the settings in the registry.

The keys are found in the following registry sub-tree (9.0 = Outlook 2000 & 10.0 = Office XP):

HKEY_CURRENT_USER\Software\Microsoft\Office\9.0\Outlook\Security
HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\Outlook\Security

Add the key (string value) Level1Remove to insert additional file types to block at the client. Multiple file types must be separated by a ";". For example: com;exe;pif;pi

Add the key (string value) Level1Add to allow a file type to be viewed within Outlook. While I cannot get confirmation of this, I believe that there is still a set of file types (perhaps Level 0) that this will not work for. So far, I've tested .exe, .com, and .vbs. All are still unviewable, even after adding their file extensions to Level1Add.

Level 2 file attachment classifications are valid only as part of an Outlook within Exchange environment. An administrator can only make changes to Level 2 file types at the Exchange level.

In addition, I am still experimenting with Outlook 2003. It appears (on my installation), that the .PFI extension (supposedly a default Level 1 "unsafe" file type) does not get blocked. I'm testing some settings to see if Outlook 2003 uses the same levels for e-mail blocking.