This appears to be a common problem and there are numerous postings
around the net.  I have not been able to find a good solutions yet
however.

Here is the situation...

I have a few clients who are using Outlook 2003 SP2 on Windows XP
SP2.  Outlook is connected to Exchange 2003, in Cached Mode.

Every once in a while (building in frequency however, becoming
annoying) emails that are sent get stuck in the Outbox.  There does
not appear to be a pattern to it, and it is not directly repeatable.

I logged onto the computer in question and sent a series of 25 emails
over a period of 30 minutes to the same email address.  All of the
emails were identical, and contained no attachments and minimal text
(outlook signature only).  Two messages (number 5 and 17 in sequence)
hung in the Outbox.  I had to move the affected messages to Drafts and
resend, which then pushed them through.

Can anyone offer any suggestions on how to troubleshoot this issue?
This may be more of a Outlook than Exchange issue, but I thought it
was worth posting here for input and advice.