This articles describes the renewal of SSL certificates for courier pop3 and imap server. This is nescessary e.g. when the certificates are expired or contain the wrong hostname.
First delete the exsiting certificates:
rm -f /etc/courier/imapd.pem
rm -f /etc/courier/pop3d.pem
Then edit the template that contains the details for the ecrtificates so that the hostname in the certificate matches the hsotanme of your server and that the email address matches your postmaster email address:
and create the new certificates:
Courier pop3 and imap have to be restarted so they pick up the new ecrtificates: