Thunderbird Community Forum

Hello.

I have added a new account to Thunderbird, and it is not syncing to show new messages. I am getting a pop-up from Tbird saying "The certificate for mail.newcreationloughborough.uk is not valid for that server ..." etc. I have gone through the procedure titled 'Troubleshooting email client warnings about invalid server certificates' to add Norton's certificate to my email app (as directed by the 'resolve' link in the 'Resolve email sync issues caused by certificate warnings' from the Norton EE Cyber Security add-on), and it tells me that the certificate is already installed.

What can I do next to get it to sync?

Have updated from 140.3.1 esr 32 bit to 143.0.1 release 64 bit TB and to windows 11 - uninstalled 32 bit and installed 64 bit and updated to windows 11 Following updates found that device sign in id (pin) was used to be in 32 bit missing from settings to access password but can show passwords. In reviewing the profile after update I note that Mozilla location service key, google location service key and safe browsing keys are missing (not sure what they were pre update). The key4.db file pre update was 1/3/22 but after update it is 10/10/25. The logins.json pre and post update is 7/9/25. I can see the default release profile and local only - use only the default release. My question is - has the 64 bit installation cleared all my keys/how can I check all my keys and how do I fix and ensure connections are secure?

Thankyou for any advice.