I reinstalled twice. Someone on the Verizon forum suggested I reinstall so I did that once using just the Windows unintstaller. Nothing changed. Then I tried again using the Avast uninstall utility and booting into safe mode. Nothing changed. ???
One other question comes to mind-what are you using for a firewall? Does anything show up as being blocked in the log? Do you have rules to allow AvastSvc.exe TCP out on port 110 for the unencrypted connection?
Already addressed in my second post in this thread. Comodo is not the problem. With just Comodo running, all mail accounts work fine in Thunderbird. With Comodo disabled and all mail filters in Avast running, I get the error message. It clearly is something wrong between the interaction of Avast and that particular mail server.