Setting up the certificate in Thunderbird
After the processing of your application is completed, you will receive an e-mail with your certificate as an attachment and a link to retrieve the certificate.
Open the link with the same browser you used to create the certificate request. Your keys are only available in this browser.
Export from Firefox
If you have imported the certificate with Firefox, it is initially only in the certificate store of this browser and you must first export it from the browser to import it in Thunderbird afterwards.
Open the settings in Firefox (Tools -> Settings), click "Advanced" and "View certificates", select "Your certificates" and click "Backup All…". Save the certificate together with the certificate chain in a file of type .p12. Since your secret key is also stored in this file, you will be prompted to select a password for protection that you will need again when importing later.
Import and set up in Thunderbird
To make your certificate, which is stored in a file, known to Thunderbird, import it into Thunderbird in the account settings of your HZB account (Options -> Account Settings), open the account and click "Security".
With the button "Manage Certificates" you get to the certificate manager of Thunderbird where you can import your certificate.
Then select to use this certificate for signing and encrypting/decrypting messages. If you want, you can decide here that every e-mail you send will get digitally signed automatically.