Pam,
You're right, my outgoing mail port is, indeed, port 80. What kind of cockamamie crap is that!?!? SMTP has been port 25 since, approximately, the beginning of time; while HTTP has been port 80.
<grumble grumble> Who the hell moves email on port 80!?
Did some double checking...we use GoDaddy to manage our email remotely. I used their auto set up tool when setting up Outlook. A check on their configuration screens shows that they take smtp traffic on port 80, 25, 3535, and 465 (ssl). I switched Outlook to port 25, and it seems to have worked. However, I went and un-checked the "well known browser processes" box, and we're back to failing to send email.
I thought you were on to something (at least related to why the webshield is preventing email traffic, if the email traffic is on the HTTP port, it would make sense).
Just got another response to my Avast trouble ticket. The suggestion this time is to uninstall Avast (using their uninstaller in Safe mode), then reinstall. I don't have time to go through all that right now, so, it'll have to wait for a little bit till I have some time to mess around with it again.
cheers
..rob