"An unknown error has occurred."

[Allan]

I am trying to delete a 'Sent message' and a box with the message an "unknown
error has occurred" pops up and will not allow me to delete the message.

Could anyone give me a suggetion on why this is happening and how to get rid
of it?

 

[Gary VanderMolen]

If one or more messages can't be deleted, apply the Microsoft fix:
http://support.microsoft.com/kb/941090

Although it mentions Outbox only, the fix works for all mail folders.