Courier with TLS connection

• Create certificates
• Create PEM file

cat /etc/ssl.key/domain_de.key /etc/ssl.crt/domain_de.crt /etc/ssl.crt/domain_de.cabundle > /etc/ssl.crt/domain_de.pem

• Edit: /etc/courier/imapd-ssl

TLS_CERTFILE=/etc/ssl.crt/domain_de.pem
IMAPDSTARTTLS=YES
IMAP_TLS_REQUIRED=0