In some circumstances, messages will become stuck in the Outbox folder
according to WinMail (even though no message may exist in the outbox
directory of eml files). These stuck messages prevent WinMail from being
able to send any messages.
Previously the only solution was to wipe out the database. I've now added a
button to my WMUtil program (http://www.oehelp.com/WMUtil/Default.aspx)
Clicking on the "Clear Outbox" button will remove all references in the
database to outbox messages. This should then enable the user to send
messages again, but since I haven't had the problem, I haven't been able to
test if it will work for those who are experiencing it.