Can I assume you have already enabled IMAP access in your Gmail webmail settings?

Here are my working Gmail settings. I use the same ones for 3 different Gmail accounts, with different user names and passwords, of course. How do they compare with yours?

Incoming Server Type: IMAP Mail Server Incoming Server Name: imap.gmail.com Port: 993 User Name: <my email address> Connection Security: SSL/TLS Authentication method: OAuth2

SMTP Server Name: smtp.gmail.com Port: 465 Connection Security: SSL/TLS Authentication method: OAuth2 User Name: <my email address>

Yup. Those seem to be the defaults. Which gives me "unable to log in at server". Both IMAP and POP seem to be enabled on my gmail. Just went to double check. But they both give me "unable to log in at server".

- Make sure cookies are allowed in Thunderbird

- Do not use a VPN while attempting to authenticate to your Google account

- Make sure there is no application running on your computer which is blocking local TCP port 80, e.g. a local web server

Cookies are allowed. Port isn't blocked. Always been trying with and without VPN - same result both ways.

Let's start at the beginning.

• https://support.google.com/mail/answer/8494?hl=en&co=GENIE.Platform%3DDesktop

You need to confirm you can log on directly to each gmail webmail account via a browser. That will prove the account/email address is alive and the password works and you can see emails on the server.

You mentioned that in gmail they had both Imap and Pop enabled. That means you must have selected the Pop option at some point in the past. Does that mean that email address is/was set up as a POP account?

IF you have a gmail account that you set up as a POP account, then gmail can get annoying. They can and do deliberately stop downloads until you Logon to the webmail account and delete a load of old emails. Gmail expects Pop account users to store emails on their computer and need you to periodically logon to webmail and delete mail from 'All Mail' especially anything that has no label. Gmail also auto stores anything you send via smtp. Pop accounts have no means of putting old deleted mail into the gmail server Trash folder, so they just get labels removed and remain in the 'All Mail' folder.

Confirm - if using account as Pop you have Logged on to the webmail account and deleted loads of old emails.

You must be able to Logon to the gmail email address webmail account via a browser (eg: Firefox) to confim you have access to that particular account before you can create the gmail account in Thunderbird.

Now Run through all the following to check everything is correct as this is the full list of everything you need to check.

1. Firewall: Access Firewall - it might be the defaulton computer or controlled by an Anti-Virus prgram. Set up Thunderbird program as 'allowed' so nothing gets blocked.

• Confirm Thunderbird is set up as allowed program.

2. VPN: Check computer for a VPN. Some Anti-Virus products now offer a VPN and I have come across some peopl who did not realise one had been enabled. Switch off VPN (or create split tunnelling and set it up for Thunderbird to use). Gmail does not like VPN as it atempts to hide your IP address, so gmail decides you might be hacker so it auto blocks access.

• Confirm VPN is switched off

3. Localhost: Do you have anything using the localhost? People who manage websites may typically use eg: Apache Xampp. You need to switch of any program using the localhost whilst setting up gmail. You can enable it again afterwards. I had to switch off Apache Xampp.

• Confirm nothing is using localhost.

4. In Thunderbird

• Settings > Privacy & Security
• Web Content
• Select 'Accept cookies from sites'
• Click on 'Exceptions' button
• Enter this : https://accounts.google.com
• Click on 'Allow
• Click on 'Save Changes'

4.1 If using old profile:

• Whilst in that area - scroll to Passwords section
• click on 'Saved Passwords'
• If you see any mention of the account you are trying to set up - select the relevant lines and click on 'Remove'
• Click on Close

5. Switch off the following as it's still experimental and has been known for some issues

• Settings > General
• Account Hub
• uncheck this checkbox: 'Create accounts in the new Account Hub'

6. Create the mail account

• Menu app > New Account > Email
• Enter name
• Enter gmail email address
• Enter password
• Select checkbox to remember password.
• Click on 'Continue'

Thunderbird by default will look for the IMAP server settings. They should be:

• Server name: imap.gmail.com
• Port: 993
• Connection Security: SSL/TLS
• Authentication Method: OAuth2
• Username = full gmail email address
• Password is the same one you use to access webmail

Outgoing SMTP:

• Server name: smtp.gmail.com
• Port: 465
• Connection Security: SSL/TLS
• Authentication Method: OAuth2
• Username = full gmail email address
• Password is the same one you use to access webmail

Assuming all is ok click on 'Done'

You should then get the gmail pop up browser type window. It will ask you to confirm you really are you and the then askif you want to allow Thunderbird access to server.

Then an OAuth token gets created and stored in the same place as all other passwords.

I can login to account via browser. I've disabled POP. Thunderbird is "allowed" in firewall. Turned off VPN. Localhost is empty. Did the settings you've mentioned. Tried to login in Thunderbird again - unable to log on at server. Same story.

Other desktop email clients also don't work. It's something on system/network level probably, but I've given up, to be honest. Maybe try again on Linux, once I switch to it.

re :unable to log on at server.

Is that the complete message ? An image of that complete error message may help.

Unable to logon is not saying your settings are wrong. The password etc has not been refused as incorrect. If creating a new account, it does not sound like you even getting to the pop up google window to set up Oauth. That implies something is blocking access.

I mean, here's a screenshot (https://ibb.co/twj3C32b). You won't gleam much from it though. It does mention settings in the list of potential wrong things. Username/password can't be wrong, it's copypasted from a password manager and it works in browser. And yes, you are correct, I am not getting to the pop up to let me login, it just fails outright. That's the whole problem. I'd love to know if there is a log somewhere that would show exactly what's happening, but also, to be honest, I've kinda given up and don't care anymore. I'm back to checking mail in browser, which sucks, but after all I've tried and looked at (not here, but I've been trying many things on my own and none of them work), I'm really feeling like it's not going to get fixed with some simple tinkering. It's something system/network level. It's either my ISP doing something weird, or my VPN having a weird adapter that affects things even when it's turned off (but i'm not going to uninstall it permanently, I need that VPN and it's paid years in advance), or it's something related to me being on Win10 and hanging on to an older version of it, but I'd rather not have Thunderbird for a moment, until I'll make a run for Linux, than let this thing to update.

So, if you know a way to get a log to know exactly what the problem is - I'll keep going. If not, I'm kinda done guessing.

re :or my VPN having a weird adapter that affects things even when it's turned off

Ok - that's a possibility. Here's a thought you need to check out. I believe a VPN can have something like a Kill Switch. A VPN kill switch is a security feature that protects your privacy in the event of an unexpected VPN (Virtual Private Network) connection drop. Maybe you switching off VPN has auto enabled the Kill Switch.

But here what doesn't make sense. I've been using this VPN for years alongside Thunderbird. And it was fine all that time. If it's actually VPN, then it's some weird "updates colliding" situation where either VPN or Thunderbird updated in a way that broke things. And, honestly, I'm not untangling thing mess without logs. I'm done guessing.

Decided to mess around with it one more evening and I actually fixed it. It was some certificate bs. I, once again, did a bunch of random things I found and one of them solved it.

Specifically I did this (cmd as admin):

certutil -verifyctl AuthRootWU certutil -generateSSTFromWU roots.sst certutil -addstore -f root roots.sst

and this:

netsh winhttp reset proxy reg add HKLM\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL /v EventLogging /t REG_DWORD /d 7 /f

I don't know which one actually fixed it. Also for a moment it seemed like it didn't do anything, even after a reboot, Thunderbird would still give the same error. But after some time I noticed that Firefox is now also failing tls handshake, but other browsers are fine, so I created a new profile, which generated a new certificate, which fixed Firefox. Then I copied cert9.db from the new profile to my initial one, and the initial profile also got fixed. And after that I decided to delete Thunderbird and all it's files, hoping that it will generate a new certificate and everything will magically work. And it actually did.

Man, I hate certificates. It's such a mess. But anyway. I guess I'm done here, and hopefully I won't come back.

My Thunderbird account has also stopped receiving emails. Sending messages works fine, but it just won't log in to check for new mail. I've been using it for over 20 years, but maybe it's finally time to explore other email client.

My Thunderbird account has also stopped receiving emails. Sending messages works fine, but it just won't log in to check for new mail. I've been using it for over 20 years, but maybe it's finally time to explore other email client.

If you have a problem then please ask for help in your own question. This question is specifically about a gmail account and the information given would normally fix almost all situations regarding gmail. In this case, the question owner did report on how they managed to resolve their particular issue, but it is an uncommon fix.

If this does not exactly match your situation, then please ask your own question. Why ? Because any comments you post in someone elses question will be sent to the person who created that question and unhelpful comments may not be appreciated. I also received a copy as I was following the question. This is a Thunderbird Support Forum; not a chat forum. Please do not post any more comments in this particular question.

You get a lot more people seeing your question and therefore increase chances of help. So let us see if we can help you by asking a question and supplying information about the issue.