Forum communautaire Thunderbird

setting up a new computer, trying to set up my gmail account on Thunderbird I get this message... Secure connection failed

' live.mozillamessaging.com uses an invalid security certificate.

The certificate is not trusted because the issuer certificate has expired.

(Error code: sec_error_expired_issuer_certificate)

   *   This could be a problem with the server's configuration, or it could be
     someone trying to impersonate the server.

   *   If you have connected to this server successfully in the past, the error may
     be temporary, and you can try again later.

  Or you can add an exception…

I have 2 machines side by side, the old works just fine , its 12 yrs old, i want to use my new one... how do I fix this ?? And yes ive tried manual settings and all that.. its the certificate in Thunderbird thats expired it says

I was forever losing the BD toolbar on the last release ot TB and had to keep uninstalling something and reinstalling it. On latest update of TB, all my settings have again been scrambled (it takes forever to go though every setting on TB!) and I've again lost the BD spam toolbar, even though it is installed and enabled. Can anyone remind me how to get it back without uninstalling and reinstalling the whole of Bitdefender, please?