Using OAUTH2 has been an option for several years and now it will soon be mandatory for Gmail. TB has that option and it's rather straightforward. You need to change authorization by going to tools>account settings>server settings and changing authentication method to OAUTH2 and then going to tools>preferences>privacy&security and remove the gmail passwords - highlight account, rightclick and remove password. After that, shut down TB and restart. You will be presented with a menu to log into gmail to grant access to TB. Once done, life should resume.

On 2-step authentication, that is not a requirement for OAUTH2.

Hello David. Thank you for your kind response. I am in tools>preferences>privacy&security and see headings of web content, passwords, junk, data collection and use, and security. Under security is scam detection, antivirus, and certificates. Under Passwords, there is a button to click "saved passwords." When I click that I see two listings for one gmail account: (1) oauth://accounts.google.com (https://mail.google.com/) and (2) smtp://smtp.gmail.com (smtp://smtp.gmail.com). For the other gmail account I only see one listing: oauth://accounts.google.com (https://mail.google.com/). When I right click on any of these three listings I get options of copy URL, copy user name, edit username, copy password. At the bottom of the box listing all my email accounts (2 gmail, 1 yahoo, 1 hotmail) I see two options on the left: "remove" and "remove all." Am I supposed to select the gmail accounts one at a time and click "remove"? And by "remove" does it mean that only the password will be removed as you instructed? BTW - when I started working through your instructions I found that one of the gmail accounts was already set for OAUTH2. The other one was not, so I changed it to OAUTH2. I closed TB, and when I reopened it I was asked to log into the account via google and give the password, which I did; then I was asked to grant access for the account I had just changed, which I did. After closing TB again and restarting, it started up without any questions. Maybe I don't need to remove any passwords? If I'm still supposed to remove the passwords, I'll need more detailed instruction on how to do that. Thank you again, and sorry for the lengthy response.

If you right click on an account, the menu allows password editing, wherein the content could be deleted. If you highlight an account (but not right click) then the remove option removes everything. The suggestion to remove password is not always needed. Since it all worked for you, do nothing more. All is well. Thanks for sharing.

I was unable to send emails through Thunderbird (TB) that was linked to my Gmail account. Suddenly all my passwords seemed wrong. And then when I started fiddling, I couldn't receive or send emails through TB. This occurred today June 7, 2022.

Please excuse my inability to speak/type in a techy way. I'm terrible with computers, but I seem to have solved my issue. So I am hoping that if I post this then it might help someone who tends to not fiddle with their computer unless absolutely necessary. I'm a Mac person.

Go into TB -> Preferences -> Privacy & Security -> Saved passwords and remove them all. Go into TB -> Preferences -> Account settings -> Server settings -> switch Authentication method to OAuth2 I did this with all my gmail accounts. Then scroll down to Outgoing Server (SMTP) and I chose Google Mail and then Edit. Switched the Authentication method to OAuth2. Quit TB and restart it. Have your passwords handy because you will need them to link everything up.

So now a few hours later, I am able to receive and send emails through TB.

p.s. I did follow what some others had written, but I had trouble understanding where to find what they were talking about. (Like where is the Outgoing Server?). Yes, I am that dweeb-y with computers.

This worked for me, thank you. I had at first forgotten the outgoing server was way down there below all the accounts, but it's all good now. Anyway, thanks for the helpful responses.

...what freakin' really REALLY sucks, is that this google mail garbage has now ceased all Windows XP users from now having an email client. Don't laugh. - there are more of us XP users than what most people think. This entire new world domination crap, that Google have put onto us, using OAUTH2 is all well an fine, but XP can not run an email client that supports OAUTH2. All browser clients Thunderbird, SeaMonkey etc, and anything else that I can find that does support OAUTH2, does not run on XP. Bare minimum is Win7 O/S or higher.

After 21 years with XP this just sucks balls not having any options at all. Why should some dopey mob tell me how to run my life and force me to upgrade ? If I could, I'd stab Google in the eye with a blunt knife.

Hey Mozilla, how about providing Thunderbird for XP with oauth2? "...yeah, that ain't gonna happen!"

You can still use TB with gmail on XP.

Tools/Options(Mac:Preferences; Linux:Edit/Preferences)/Advanced/General/Config. editor, double-click general.useragent.compatMode.firefox to true.

There is a bug with TB 59 that can be fixed by changing preferences.

OMG!!! I spent Hours, Weeks, MONTHS on this issue. I was ready to jump (I Only live on first floor). BUT, I FINALLY Solved it. I was going through HOOPS with Google NOT letting me Authenticate.

Solution! - USE FIREFOX BROWSER as your DEFAULT Browser.

My stupid mistake, which sent me in circles FOREVER was believing that because I wanted a GOOGLE OAuth, I SHOULD use a google browser, which is usually my default *ducking*. WRONG!!!

It took MONTHS for me to try Firefox. Ahhhh. it worked first time. Smooth as silk.

May not be the solution for everyone, but it FINALLY Worked for me.

...what freakin' really REALLY sucks, is that this google mail garbage has now ceased all Windows XP users from now having an email client. Don't laugh. - there are more of us XP users than what most people think. This entire new world domination crap, that Google have put onto us, using OAUTH2 is all well an fine, but XP can not run an email client that supports OAUTH2. All browser clients Thunderbird, SeaMonkey etc, and anything else that I can find that does support OAUTH2, does not run on XP. Bare minimum is Win7 O/S or higher. After 21 years with XP this just sucks balls not having any options at all. Why should some dopey mob tell me how to run my life and force me to upgrade ? If I could, I'd stab Google in the eye with a blunt knife. Hey Mozilla, how about providing Thunderbird for XP with oauth2? "...yeah, that ain't gonna happen!"

XP ???

Are you serious???

"After 21 years with XP," . . . XP's extended support ended on April 8, 2014 . . . gee, you're only 8.5 years behind!

Forget XP dweeb!

Do yourself a favor: AT LEAST upgrade to Windows 10 Pro.

As for, ". . . there are more of us XP users than what most people think," I am LMAO.

All you XP users are so far behind the curve.

You cannot have adequate security on your systems.

Todays websites will not load in XP.

Beegeezus . . . GET RID OF XP !!!