Open the eBlocker SSL configuration page.
Click on the button "Add certificate" and download the certificate to your downloads directory.
Go to the Thunderbird menu and click on Options.
Go to Advanced, choose "Certificates" and click on View Certificates.
After the Certificate Manager opens, choose "Authorities", click on Import and choose the eBlocker certificate from the downloads directory.
Open the eBlocker certificate and make sure that the first checkbox "This certificate can identify websites" is selected. Confirm with OK.
Confirm the Certificate Manager and the settings with OK.
The certificate is now inserted into the Thunderbird email application.