This tutorial describes the steps to renew the SSL Certificate of the ISPConfig 3 control panel. There are two alternative ways to achieve that: Create a new OpenSSL Certificate and CSR on the command line with OpenSSL. Renew the SSL
Import SSL Certificates in Thunderbird
SSL certificates are used to sign and encrypt/decrypt mails in thunderbird via S/MIME. If you have got a certificate that you want to use to validate your identity, import it as follows: Open Thunderbird and go to Edit > Preferences: