My ISSP changed to an Office365 system for my emails, so needed to migrate. Could not find any help files on this except an old one from Stamford Uni, but did find a Moz help file for setting up a new Thunderbird acct on Office365. I did not try to create a new account, but followed all instructions (as far as I could tell!) to modify setttings of existing POP acct (port numbers etc etc. The incoming mail works fine. The outgoing connects with the server, but has ALWAYS "timed out" and does not send. I have restarted Thundebird.