Fixes
• POP message retrieval stopped after a network error occurred and connectivity was restored
• Reused SMTP connections sometimes silently disconnected, causing timeouts
• Thunderbird could freeze if saving a sent message to IMAP failed
• Creating OpenPGP keys with no expiration was not possible
• News reader did not always issue GROUP command after authentication with remote server, preventing Thundebird from displaying or refreshing news from the server