Use this Microsoft fix:
http://support.microsoft.com/default.aspx/kb/941090
"Messages may be stuck in the Outbox when you use Windows Mail on a
computer that is running Windows Vista"
Although Outbox is the only folder mentioned, it will remove stuck
messages from all folders.
Gary VanderMolen
"Marlis" <Marlis@xxxxxx> wrote in message news:13870E4B-9D87-4AC8-A36D-BAACFBA58158@xxxxxx
Quote:
> When trying to delete the Sent Items folder, I get the well-known "Unknown
> Error" message and nothing will delete, by hand or otherwise. Help please?
> --
> Thanks - M