Difficult to say - networking may be involved. Does the problem change if you have Windows started in Safe Mode?

Please post your results

Thanks Wayne. Unfortunately Safe mode made no difference.

I then went and again checked Melbpc's recommended settings for Gmail through Thunderbird and noticed they no longer have OAuth2 for authentication so I changed that to normal password and it started reading my mail again. Also changed the outgoing server settings similarly and crossed my fingers but unfortunately on my pc using Thunderbird it now won't send or save drafts.

One step closer now. 🙂

hello!thank you for reaching out!It sounds like Thunderbird has suddenly stopped working with your Gmail accounts, even though everything else seems fine. Since you've already tried turning off NordVPN (and the issue persists), let's go over some common potential causes and solutions to get Thunderbird working again on your Windows 10 PC.Summary of Steps to Try:

   Check Gmail security settings (enable less secure apps or re-enable IMAP).
   Verify IMAP/SMTP settings (ensure they match Gmail’s settings).
   Create a new Thunderbird profile to check for profile corruption.
   Clear Thunderbird’s cache from the Network & Disk Space settings.
   Temporarily disable your firewall/antivirus to check for interference.
   Update Thunderbird to the latest version.
   Test Gmail with a native email app or browser to check if the issue is specific to Thunderbird.
   Check Google account security for any alerts or changes that might block access.

I hope one of these solutions helps you resolve the issue with Thunderbird! If the problem persists, please let me know, and we can dive deeper into other possible causes. 😊

"Thanks Wayne. Unfortunately Safe mode made no difference.

I then went and again checked Melbpc's recommended settings for Gmail through Thunderbird and noticed they no longer have OAuth2 for authentication so I changed that to normal password and it started reading my mail again. Also changed the outgoing server settings similarly and crossed my fingers but unfortunately on my pc using Thunderbird it now won't send or save drafts."

Thanks for the update! It sounds like you’ve made some progress, but you’re still encountering issues with sending emails and saving drafts. It seems like the switch from OAuth2 to password-based authentication for both incoming (IMAP) and outgoing (SMTP) mail servers has allowed Thunderbird to read your Gmail, but it’s not resolving the full issue.

Here’s how we can troubleshoot and work through the problem of sending emails and saving drafts: 1. Double-Check SMTP Settings

Since you're able to receive emails but not send them, it’s likely an issue with the SMTP (sending) settings.

Gmail SMTP settings:

   SMTP Server: smtp.gmail.com
   Port: 587
   Encryption: STARTTLS
   Authentication method: Normal password
   Username: Your full Gmail address (e.g., yourname@gmail.com)

Steps to verify:

   Open Thunderbird.
   Go to Tools > Account Settings.
   Under Outgoing Server (SMTP), select the Gmail SMTP server and click Edit.
   Ensure the authentication method is set to Normal password, and the username is the full email address.
   Click OK to save changes.

After this, try sending an email again and check if the issue is resolved. 2. Check for SMTP Connection Errors

Thunderbird might not be able to connect to Gmail’s SMTP server properly, which could prevent sending emails or saving drafts.

Solution:

   Go to Help > Troubleshooting Information.
   Scroll down to the Logins section and look for any connection errors related to your SMTP server. If there are any authentication or connection issues, they might appear there.

You could also enable SMTP logging to track the issue in more detail:

   Close Thunderbird.
   Open Run (Windows + R) and type thunderbird.exe -smtp-log.
   Open Thunderbird and try sending a test email. The log file will be saved, and you can review it for any errors related to the SMTP server connection.

3. Test Draft Saving:

There might be a problem with local drafts not being saved correctly. If drafts are not being saved in Thunderbird, it could be related to the IMAP settings or a conflict between local and server-side storage.

Solution:

   Go to Tools > Account Settings > Server Settings.
   Under the Drafts folder section, ensure that Keep drafts in is set to "Drafts" on the server (to save drafts in Gmail's cloud storage, not locally).
   If you want to store drafts locally, choose Local Folders instead.

Also, check if Thunderbird is able to connect to the drafts folder on the Gmail server:

   In Thunderbird, click on your Drafts folder and make sure it syncs correctly. If the folder appears empty or unresponsive, there may be an issue with the IMAP connection.

4. Test Sending Email Without VPN:

Since you mentioned using NordVPN, it could be affecting Thunderbird’s ability to send emails. Some VPNs might block certain ports or protocols used by email services like Gmail.

Solution:

   Disconnect from the VPN and try sending an email again. If the email sends successfully, it suggests that the VPN might be interfering with Thunderbird’s connection to the SMTP server.
   If this works, try adding an exception for Thunderbird in your VPN settings or use a different VPN server.

5. Check Gmail’s Security Settings:

Even though you've switched back to password-based authentication, Gmail’s security settings may still block certain connections.

Solution:

   Ensure that your Gmail account doesn’t have any alerts or security blocks. Log in to Gmail in a web browser and check for any suspicious activity or "blocked sign-ins". If you find any, you may need to allow Thunderbird to connect again.
   Try logging into Gmail through a web browser and check for any security prompts (e.g., confirming that you are trying to connect via Thunderbird).

6. Clear Thunderbird’s Cache:

Sometimes, Thunderbird’s internal cache might cause issues with syncing drafts or sending emails.

Solution:

   Go to Tools > Options > Advanced > Network & Disk Space.
   Click Clear Now under Cached Web Content to clear Thunderbird’s cache.
   Restart Thunderbird and test again.

7. Test with a New Profile:

If Thunderbird's current profile is corrupted, it could cause inconsistent behavior like not sending emails or saving drafts.

Solution:

   Try creating a new profile by following these steps:
       Close Thunderbird.
       Press Windows + R, type thunderbird.exe -P, and hit Enter.
       Create a new profile and add your Gmail account to it.
       Test whether this new profile resolves the issue with sending and saving drafts.If the problem persists, please let me know

Thank you very much for your suggestions sakura. Part of me wants to try those suggestions one by one to pin down the specific cause but unfortunately my medical condition (PLS, "little brother" to ALS) means I can really only get to my pc occasionally when my wife is available to make sure I don't fall trying to get in.

When I do, the first thing I am going to do is uninstall Thunderbird completely, reboot and reinstall. If that doesn't work I'll then work through the steps you kindly provided. Thank you again! 👍🏻

The specific issue is Gmail does not support the use of Normal password and has not for some time. like 2022 trime see https://support.mozilla.org/en-US/kb/automatic-conversion-google-mail-accounts-oauth20

Any "fix" that involves using a connection that does not use oauth will fail, so it is much better to get rid of the software or poorly imposed restrictions that are causing the issues now than try again in a few months when you have had time to forget what you have learned through this.

Note the link is a support article for oauth issues with gmail that was written after Thunderbird imposed a universal update in authentication methods used for gmail to oauth in 2022.

If by melbpc you are referring to the melbourne PC users group, they are in no way an authoritative figure in settings prescribed by Google. For that you would refer to google and they do publish their expectation of the settings you must use. There is link in the article to the google help documentation that sparked the automatic updates.

What I have noticed over the years is things like cccleaner and antivirus proframs are often the direct cause of connection and oauth failures because they delete Thunderbird settings files and turn off the necessary cookies for oauth to actually setup.

Generally thew are actually written by folks that think they know necause it used to work for them.