stumpypete
Try this.
In Outlook Express, under Tools/Accounts select your account, then click on Properties. Click on the advanced tab. Set 25 for the SMTP port and 110 for the POP3 port and make sure the box for "This server requires a secure connection (SSL) in unticked for both SMTP and POP3. Click OK, then close, then exit Outlook Express. Don't try to send or receive mail at this time.
Bring up the Avast main screen, select Real time shields, then mail shield, then expert settings, then SSL accounts. Highlight any entries in there and delete them, one at a time. When they are all gone, click OK to exit back to the main Avast screen, then exit that.
If you have a self teaching firewall like Zone Alarm that asks for clearance for your email client the first time you send/receive emails after the firewall has been installed, delete any permissions in the firewall relating to outlook express.
Now reboot the computer.
When it is back up running, start outlook express and try a send and receive on you specific account. When the firewall asks for permission, make the acceptance permanent.
You will find that the SSL settings for Avast's mail shield will regenerate on their own, even though in your case you are not using SSL.
Let's know whether that solves your problem.