Hi guys. I made a video tutorial quite a while ago showing how to retrieve a free Comodo e-mail certificate from here using Internet Explorer, and then import it into the free e-mail client, Thunderbird.

My free Comodo e-mail certificate recently expired. So I followed my video tutorial exactly as I did a year or so ago, and got this error:

Sending of message failed. Unable to sign message. Please check that the certificates specified in Mail & Newsgroups Account Settings for this mail account are valid and trusted.

More info’…

So after fixing the problem, I decided it might be usefull for others if I posted my fix here. So here goes…

  • Once you’ve retrieved your free e-mail certificate from Comodo, open Internet Explorer.
  • Go Tools>Internet Options>‘Content’ tab>Certificates.
  • Select your new certificate from the ‘Personal’ tab.
  • Click ‘View’.
  • Select the ‘Certificate Path’ tab.
  • You will now see the tree of linked certificates which are required. Export each certificate and import them into Thunderbird (some may already be in Thunderbird): View each certificate, select the ‘Details’ tab, then ‘Copy to file’.

And that’s it!

Happy Security! Happy Privacy! Happy Christmas! And a Happy New Year! ;D :-TU