dp,
Avast and OE 6 work fine togther.
Your server settings should be both 127.0.0.1 with the server names:
username#pop.freeserve.com
username#smtp.freeserve.com
If the server names ARE NOT preceeded by your freeserve username, then Avast is not properly configured.
You can use the Mail Protection Wizard found in the Programs folder, or set it up manually though OE Options.
I can give you instruction if you need.
PS: You do not need to use the Eicar to test Avast.
If you enable the "Insert Message into clean mail" for POP, SMTP and IMAP, then you can "see" if Avast is scanning the email. This also is very easy to do within the On Access Protection Control (right click on the A ball in the tray.....find Internet Mail module on the right....Click on it to open the menu....then, open the tabs for POP, SMTP and IMAP. Check the box to insert message into clean mail.
Now, send yourself an email. You should see a note in the return email "Incoming..Avast" and "Outgoing Avast".
Good luck.