How to renew the SSL certificate for dovecot, CentOS, Webmin

As root: First make a backup of the existing key and certificate file

# cd /etc/pki/dovecot
# cp -a certs/dovecot.pem certs/dovecot.pem.old
# cp -a private/dovecot.pem private/dovecot.pem.old

Create the new SSL certificate for two years:

# openssl genrsa -out private/dovecot.pem 1024
openssl req -new -x509 -key private/dovecot.pem -out certs/dovecot.pem -days 730

Restart Dovecot:

# /etc/init.d/dovecot restart

To see the start and end dates for the certificate:

# openssl x509 -dates -in certs/dovecot.pem