When you reset the password on the gmail webpage, did you edit or remove the one used by TB in Tools/Options/Security/Passwords/Saved Passwords? Is the authentication for the incoming and outgoing servers set to OAuth?

http://kb.mozillazine.org/Using_Gmail_with_Thunderbird_and_Mozilla_Suite

it was some strange gobblyledegook one and I changed it to match my new google/gmail one - but made no difference.

Got exactly the same error message

incoming authentication OAuth outgoing was normal password - changed it to Oauth - one email sent THEN the next one failed AGAIN - same message... sob sob!

see my first screen shot - then after it wont take my new password it gave me this error message (NB it says smpt.GOOGLEMAIL.com and not gmail.com as in my settings

AAAGHH just checked 'saved password' and it's changed back to random stuff again -

changed it back, had to sign in to gmail again and it sent OK

3 tests sent successfully...

-- and failed again

Try removing all passwords/tokens from Saved Passwords, set OAuth authentication for incoming and outgoing servers, restart TB, and go through the OAuth process where you enter your normal account password and a token is stored in Options.

worked once (to send 1 email) then failed again. removed passwords and repeated it ... no joy rebooted pc - BUT THAT DIDNT HELP EITHER

sorted I think

under >account settings I changed outgoing server to smpt.googlemail.com (outgoing server still set at smpt.gmail.com) and it SEEMS to be working. Heaven knows what changed it over the weekend, maybe an update?

I MAY be back but THANK YOU

For the server name, make sure it's smtp, not smpt.