On Dec 13 2006 I bagen receiving the following error when sending:

The message could not be sent because the server rejected the sender's
e-mail address. The sender's e-mail address was 'my e-mail address'.
Subject 'My Subject Line', Account: 'My pop account', Server: 'My
smtp account', Protocol: SMTP, Server Response: '550 5.0.0 Access denied',
Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC78
(Info within are details I deleted for this newsgroup post)

Running XP Home. Can send mail from WebMail so ISP says not their problem.
MS says "call Dell." Dell says "all is functioning fine, must be ISP
problem." Circle begins again.

Have reset account information, removed and reloaded OE6, deleted
'outbox.dbx'. Recently configured OE6 on new computer with same e-mail
account data and had same problem. I have disabled e-mail scan in my AV
program. Looking for more ideas.