Never seen it. But I'm still thinking of some local add-on. Anyway, it might help to see if it's the PC that's doing it or if it's the users profile.
If you can reproduce the problem (find a mail that consistently disappears into the deleted folder on the affected PC's) see what happens if:
a) You send it to the same user and he logs on on a 'normal' PC.
b) The regular user of a 'normal' (you as administrator, for example) logs on at an affected PC.
If only the user is affected and not the PC, delete his profile and remake it. Than the problem should be solved.
Hope this helps.
I am running exchange 2000 and have noticed on some of the PCs that Outlook occasionally puts mail directly into the deleted items folder. I have checked the rules and there are none and I know it isn't the spam filter as other people have recieved the message correctly. Has anyone encountered this problem before or have an idea on how to fix it? The PCs are running Windows 2000. Thanks.