GOOD THING I MADE A COPY OF THIS MESSAGE. IT TIMED OUT BEING SENT. I have two '''gmail '''accounts, one '''yahoo''', and one '''hotmail''' on my HP laptop, running Windows 10. I've been having server authentication problems with Thunderbird on all of them (''''except ''''hotmail) since '''9/22/21''' for incoming mail and '''9/17/21 or 9/20/21 '''for outgoing mail. Each account gives me the "failure while connecting" message. Screen shots attached. '''Hotmail '''often gives me "your email was not sent; try again later" message. BUT it '''has '''sent the message and it has been received! Sorry, no screen shot of that error message. I don't remember the terminology, but I have "listed" Thunderbird as safe/allowed to log in on my behalf with each of my accounts. From the PC, I am able to log in to all of these email accounts directly with the same user/passwords entered in Thunderbird. My Galaxy S7 Smartphone successfully sends & receives from each of these accounts using a different mail client. Please let me know if you need information on the server set ups. Until today, I did not realize the extent of this issue. I really need help! Thanks.