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"
That page offers two download options. Unless you know for sure
you have 64-bit Vista, use the 32-bit option.
--
Gary VanderMolen, MS-MVP (WLMail)
"Alabama" <(E-Mail Removed)> wrote in message news

E2482BF-061C-41F5-A4F0-(E-Mail Removed)...
> I cannot delete an unsent message, and it prevents me from sending any
> others. How do I get rid of it?
> --
> Alabama