I've been struggling with Avast/Thunderbird/SSL for more than an hour now.
You say you've set TB to "never use SSL". Where do you see that option, i can't find it in Thunderbird 3.1.2. But the TB settings that work for me are in Tools>>account settings, then choose the following in the left side of the window (and change the options on the right side)
Server settings: Security settings -> connection security: none, authentication method: password transmitted insecurely (that last one might differ in your case but that's what my provider tells me).
Outgoing server (SMTP): choose an smtp server, then click edit. Set the same as for pop3 (connection security: none, authentication method: password transmitted insecurely).
With those settings i can send and receive emails and they're being scanned too (you can see this in the main avast window>>real-time shields>>mail shield (expand the "shield traffic" bar to make the graph visible). Whenever a mail is scanned, you should see a bar in the realtime graph and under the graph there's a text showing which email was the last to be scanned).
By the way, i didn't know about the redirect settings until i read about them in your post. I've been trying to set up SSL with other settings (main window>>real-time shields>>mail shield>>expert settings>>SSL accounts and added the (i think) proper entries there. Then i read your post, looked in the redirecting settings and saw that the SSL ports weren't even listed there so i added them. If i enable SSL encryption in TB the emails are blocked (or let through but unscanned, if the SSL ports are not listed in Avast redirect settings), but if i use the above settings i can send and receive and the mail is scanned. I'd like to verify that encryption was actually used though, i don't know how to do that :/
