Importe a PKCS 12 into Thunderbird

Follow the instructions here under to import a PKCS 12 (.p12 or .pfx) into Thunderbird:

• Go to Tools / Options / Privacy
• In the Security tab click on View Certificates
• Click on Import
• Select the PCKS12 certificate file
• It might ask you for the master password for the software security device. Enter your master password or create on and click OK
• It will ask you for the password protecting your personal certificate. If your .p12 or .pfx file has a password, enter it here, otherwise leave this field empty. Then click OK

Your certificate has been imported. If your PKCS12 file holded a certification chain, it had been imported as well.

Now configure ThunderBird: Signature / Cypherment with Thunderbird