Gmail is stopping what they consider less secure apps connections and use of normal password. It means you have to OAuth2 for Authentication Method.

Thunderbird has made alterations so now both POP and IMAP accounts can use OAuth2 for gmail. Have you done all of the following?

• Select 'Menu app icon' > 'Preferences' > 'Privacy & Security '

Under 'Web Content'

• Select 'Accept cookies from sites'

It may also be a good idea to make exception:

• Click on 'Exceptions..' button
• Enter: https://accounts.google.com
• Set to 'Allow'
• click on 'Save Changes'

Now make changes to Account Settings:

• Right click on gmail pop/imap account name in Folder Pane and select 'Settings'

This opens the Account Settings in new tab The pop/imap account name should be selected Look bottom right for Outgoing Server (SMTP)

• Click on 'Edit Server _SMTP' button
• Set Authentication Method : OAuth2
• Click on OK

Now set the incoming authentication:

• select 'Server Settings' for gmail account
• Set Authentication Method : OAuth2

Exit Thunderbird and wait a few moments for background processes to complete Start Thunderbird

Gmail will prompt you to enter gmail email address and normal password you use to access webmail account. Follow instructions. It will ask this to allow Thunderbird to access server.

An Oauth token will get stored in Thunderbird - same place as passwords and from then onwards Thunderbird will use it to access server.

Hi, thank you very much for your help. I followed all instructions. Unfortunately, it has not solved the issue, Thunderbird still rejects my Gmail password even though it is a password registered in Thunderbird account settings…

I believe you need to also remove current Gmail password.

Additional:

Note: Gmail may advise to switch on 2 step verification. This is not necessary because you are using OAuth.

Some people have needed to remove the old stored passwords.

• Menu app icon > Preferences > Privacy and Security
• Under 'Passwords' section
• Click on 'Saved Passwords'
• Select the mailbox://(if pop), imap:// (if imap) and smtp:// lines and click on 'Remove'.
• click on 'Close'

Restart Thunderbird and enter password at prompt

Check if this applies to you: Some people run a localhost server eg: Apache This must be switched off and then retry. You should be able to use the google prompt. You can switch Apache back on afterwards. Note: In some Linux systems Apache may have been auto installed.

If you find you keep being asked for password and in :

• 'Menu app icon' > 'Preferences' > 'Privacy & Security '

You discover passwords and cookies are not being saved then do this:

• Menu app icon > Help > More Troubleshooting Information
• Under 'Application Basics' - Profile Folder - click on 'Open Folder'

This opens a new window showing the contents of your current in use profile name folder.

• Exit Thunderbird now - this is important.

Look for the following files and delete them.

• cert8.db - obselete file
• key3.db - obselete file
• pkcs11.txt (some people report this file missing)
• secmod.db - obselete file
• session.json
• xulstore.json

NOTE: Do NOT delete:

• key4.db
• cert9.db
• logins.json

Start Thunderbird New pkcs11.txt, session.json, xulstore.json files will get created.

Retry entering password etc at prompt.

Thank you for your helpful suggestions. Did exactly what you listed, but still am not able to get into Thunderbird.

Are you running the latest version of Thunderbird? If no then update it.

Please exit Thunderbird and then Access Firewall. The Firewall may be controlled by an Anti-Virus program. Is Thunderbird listed as an allowed program ? If no, then you need to set Thunderbird as an allowed program. If yes, some Anti-Virus products get confused and think the new update is different program. So, in Firewall, locate Thunderbird and block it, ok it, then access Firewall again and set to allow and ok it.

What Anti-Virus are you using?

Then start Thunderbird.

Do you get the prompt by gmail in a browser type looking window to enter email address and password to allow Thunderbird access to server ?

I have latest version of ThB. ThB not listed in Firewall. And when clicking "Add App" it is not in the list System32 that opens. My Antivirus is Sophos. Yes when I installed the latest ThB earlier Gmail did ask me to enter email address and password.

RE AntiVirus Firewall - allow email:

• https://docs.sophos.com/esg/endpoint-security-and-control/10-6/help/en-us/esg/Endpoint-Security-and-Control/tasks/html_gs_07_allow_email.html

You have to find out if the Anti-Virus is blocking access.

Perform two tests: Test 1. Exit all programs and restart computer in 'Safe Mode with Networking', you may need to use an ethernet cable between computer and router. This will properly disable anti-virus and use only basics. Start Thunderbird Note results.

Test 2. Start computer as normal. Disable Sophos Anti-Virus which also controls Firewall, this should allow Windows to use the built in AV and Firewall. Set up Windows Firewall to allow Thunderbird. Start Thunderbird. Note results.