On Thunderbird's side, all you have to do is right-click your Gmail account, select Settings. Under the Default Identity heading, click the Edit SMTP Server button and change Authentication method to OAuth2. Close the dialog then go to the Server Settings section under your account, then make the same change there. Repeat this for all your Gmail accounts. Finally, open Preferences > use the search box to find Saved Passwords and click it. Delete the entries for your Gmail accounts then Get Messages. You will be presented with a webpage to sign in to your Google accounts and grant Thunderbird access to your Gmail mailboxes.

Thanks that seems pretty straight forward - I will try it next week - when they turn on the 2 step verification and update here with any issues ... Still looking at solutions for my other problems...not straight forward - really angry with google right now!!!!

OAuth2 authentication has got nothing to do with 2-step verification.

As long as OAuth2 authentication is set up for Gmail in Thunderbird (which should be anyway by now, because it won't work otherwise), nothing changes for Thunderbird when Google enforces 2-step verification.

Having said that, you'll get another prompt for the second factor when logging into your account though. Typically the second factor will be your phone. So for this to work with multiple Gmail accounts, you'd also need multiple phones, each one associated with one account. There are other options for what to use as second factor.

All this is a Google thing, and not specific to Thunderbird. 2-step verification is always needed when accessing a Google account, e.g. with a web browser.

Update - so on one account - the multiple user one - two step verification was activated on Nov 9. No-one was logged out etc and when I went to settings I could just turn it off -without any 2 step verification. Thunderbird continues to work as expected...my other account so far nothing has happened... Obviously this was just a way of trying to force people to activate it ... which if you don't have a back up/ check it regularly or have lots of confidential info or use the same password for lots of sites especially if they are all ie 'password1' - it is probably a good idea. But in my case -for these email addresses - really not needed or helpful! I am still looking at gmail alternatives - this waste of my time was the final straw... Thanks again for the help - I am bookmarking for future ref...

I am still looking at gmail alternatives

Have a look at GMX, I find the service refreshing. So not google you will think you went back to 1990 and very popular in Europe. It might have something to do with the company being German so privacy is important. None of the marketing garbage either

Sorry - been catching up after wasting so much time worrying/trying to sort this google hassle - which turned into a non-problem!!!! (still annoyed!) Can I ask you a couple of questions about gmx - specifically how the mail collector works? I currently have a google account I use in a similar way - have several email addresses which forward to it and I can reply as if from any of those accounts. (Mostly hotmail/outlook) Google have faffed around with it over the years ... which has made it less convenient and not sure exactly where I am up to with all the accounts/ so no longer work as I wanted them to but the ideal is.... For a couple of them (shared accounts) save a copy of the email in the relevant inbox (outlook lets you do this) and (ideally) for my replies as that address to appear in the sent email of both the forwarding email and the gmail 'collector' email (although to get round this not happening I can bcc the sending address in a reply so there is a copy in the inbox for everyone else to see) For some I don't want any messages (inbox or sent) or contacts stored in those accounts. (I set my gmail up after someone tried to hack my main hotmail email address - one I've had for 25ish years -so many incorrect password attempts I got locked out...) I don't give out my gmail email address to anyone - so at least it doesn't appear in anyone's contacts. (They all also go to my thunderbird which has a local folder archive of older messages) So how would this work with the mail collector in gmx? I was looking at mail.com - I would need a paid for account ($30ish a year) to enable imap/pop but I'd happily pay a small amount if that stops my data being used... (I do periodically make donations to open source/free software like Mozilla, Linux mint, Libre office etc really appreciate that they exist...)

Thunderbird is a mail aggregator, so I have to ask why you would be wanting all your mail in the hands of a single online entity anyway. Why not allow Thunderbird to aggregate your mail as it is intended to do.

I could be being stupid (highly possible) but I want to be able to check my email on my phone - and I don't think I can do that with thunderbird? Also want to be able to check for latest emails even if I didn't have access to my computer without having to log into multiple sites ... And ideally want a couple of the accounts to just be forwarding ones... (I do back up my thunderbird and in theory archive my emails to thunderbird local folders) I thought an advantage of thunderbird was the emails are on your hard drive - you can access them off line - and even if you lost access to your web based email provider you would have the ones you had already downloaded...

I could be being stupid (highly possible) but I want to be able to check my email on my phone - and I don't think I can do that with thunderbird?

There is no Thunderbird app for mobile platforms (Android, iOS, etc) if that's what you're asking. Using Thunderbird to check/aggregate mail on your PC does not in any way prevent you from doing so on your phone. Your phone already has a mail app for that (you could always install an alternatve app if you want) and all you have to do is setup the accounts you wish to access on phone. The app on your phone will be doing the same thing that Thunderbird is doing on your PC. I use Thunderbird on PC and the Gmail app on android for my main accounts, so both PC and phone have access to the same mailboxes.

Also want to be able to check for latest emails even if I didn't have access to my computer without having to log into multiple sites ...

Simply add/setup those accounts on your phone's mail app. Thunderbird has no role to play here.

(I do back up my thunderbird and in theory archive my emails to thunderbird local folders) I thought an advantage of thunderbird was the emails are on your hard drive - you can access them off line - and even if you lost access to your web based email provider you would have the ones you had already downloaded...

That's right.

Thanks I have got rid of gmail on my phone - use the app that comes with Lineage OS. I can't use it to reply as one of my other accounts but I can read messages. I think I might look at rethinking how I use my emails altogether... Thanks again

lucky67 said

(I do back up my thunderbird and in theory archive my emails to thunderbird local folders) I thought an advantage of thunderbird was the emails are on your hard drive - you can access them off line - and even if you lost access to your web based email provider you would have the ones you had already downloaded...

That's right.

Only if your accounts are POP. Local stored email in an IMAP account is better considered a cache. It could all be deleted simply because you have lost access to the IMAP account that the mail is synchronized to.