Recently I had a newly minted gmail account. I tried setting it up with Thunderbird, and no dice, even when I turned on the "allow insecure apps" option on the google side. It would seemingly do everything as various explantions say it should, but then it announces "Configuration could not be verified -- is the username or password wrong?". Well, I was just on google as part of your process seconds ago and google accepted my username and password, so what the heck is your problem? You would think I wouldn't be the only person in the world trying to use Thunderbird with gmail.
Amusingly, immediately after this I tried mutt. This involves starting with a prototype muttrc file and editing a few lines in it. It worked and I was receiving my mail in less than 5 minutes.
Next I tried Claws email. Their setup dialog is less than self documenting, but with the help of some online posts, I was able to provide what it wanted. In summary, I select IMAP on the receive settings page, take all the other defaults, give my username as fred@gmail.com in two places along with my password (in the same two places) and I was in and looking at my mailbox.
All I can say is that I am thankful that once years ago I managed to set up Thunderbird with email for my main account because it is clearly impossible now. Just one more thing that irritates the hell out of me with Thunderbird.
Adventures in Computing / tom@mmto.org