ouau has no effect?!

I tried ouau here at work, and we’re using Office 2002/XP. It finds the correct Office version, I’m able to make changes to the blocked extensions, which I can verify by restarting the program: it finds the new settings. But the new registry-setting resort no effect: right-click and send-to-mail-recipient of a unblocked extension (e.g. .EXE) still results in Outlook saying that the attachments are potentially unsafe. What’s going on here? Something to do with (group)policies?

Update: I think I already know: Exchange administrators can add/remove Level 1 and/or Level 2 extensions within the Exchange-server settings. This can not be overruled by the Outlookclient. So, I guess I’ll have to find another way to test other Office versions.