To use normal password authentication, enable access by 'less-secure apps' in the Google security settings. If you have two-step verification on the account, use an app password in place of the regular account password.

http://kb.mozillazine.org/Using_Gmail_with_Thunderbird_and_Mozilla_Suite

sfhowes,

I appreciate your suggestion. However, I have those settings currently set and still have the problem.

So, it's some other cause.

Thanks

agent86fl said

sfhowes, So, it's some other cause.

The error condition comes about when Google want to notify you of something using the login process on their web site. Usually one of their dumb "security checkups" It has nothing to do with Thunderbird at all. If your getting the message, ask google why they are offering it. It is not a Thunderbird error. Thunderbird is simply offering to you the error google provided when they declined the log in attempt.

Same problem here. It started today for me. Replied to an email using a Gmail account and I got a popup to login via the Gmail site. I, too, have "allow less secure devices" enabled. Oddly, Thunderbird did not autofill my password in the login, even though it's set to do so.

Google are moving slowly to remove less secure devices. I suggest you use oAuth, then the web login requests will probably stop as that is their chosen method of authentication.

I have outlook.com requesting my password for hotmail and not my other gmail account? Everything still works though I can still send and receive emails. I put in my password but it didnt work? So now I just delete the banner when it pops up but I would love to get rid of the bastard of a thing. Its annoying. Could it be Phishing Malware even?