Thursday, January 25, 2024

Resolving invalid mail server certificates with Thunderbird

It has been a long time not dealing with this error and I almost forget about it.   Now it is a lot simpler to fix this than before.  There is no need to export Avast certificate and then import it back to Thunderbird.

  • Go to Thunderbird Settings and select Privacy & Security.   
  • Scroll down to locate Manage Certificates....


  • Certificate Manager window will be shown.
  • Ensure to select Authorities in the Certificate Manager window.  Then scroll to the row of Avast Web/Mail Shield, select the certificate and then choose Edit Trust....


  • Grant trust to the certificate and then click OK to exit.  In my case, I only need this: "This certificate can identify websites" since I manage my personal mailboxes.


That's.