I was getting the following error in my log file and I couldn’t connect to my imap server using Thunderbird.

Mar 1 13:35:19 ltps imapd[12525]: imap service init from 192.168.1.42
Mar 1 13:35:19 ltps imapd[12525]: Unable to accept SSL connection, host=dave [192.168.1.42]
Mar 1 13:35:19 ltps imapd[12525]: SSL error status: error:1408F10B:SSL routines:SSL3_GET_RECORD:wrong version number


It turned out being interference from avast anti virus on my desktop causing this. Turn off it’s IMAP checking to work around this.