The above seems to be a recurring problem with no apparent fix.

   My experience is
   Outlook 2003 fails to send email, email hangs in outbox
   The error message seems to point to a provider problem however I
have
been able to send email without a problem using the same equipment
account etc useing Outlook Express.

   Recreating the account, pst files etc several times made no
difference.
The Outlook test message always worked.

   Noticed that I could actually reply to the test message without
problems
but any other new email could not be sent.

   To make a long story short I changed some settings in     TOOLS /
OPTIONS / MAILFORMAT

   Change HTML to PLAIN TEXT and remove the check marks that
correspond to
useing word as your email editor.
   new email is now being sent.

   Cheers Bill D