Testing Mail Server SSL
Intro
When deploying new SSL certificates on the mail server, this is my prefered way of thesting them.
Testing
Testing the SSL certificates provided by the server can be done on any Linux, macOS, unix like machine by using openssl.
IMAP via SSL
Port: 993
# openssl s_client -showcerts -connect mail.example.com:993
POP3 via SSL
Port: 995
# openssl s_client -showcerts -connect mail.example.com:995
SMTP via SSL
Port: 465
# openssl s_client -showcerts -connect mail.example.com:465
SMTP via TLS/StartTLS
Port: 857
# openssl s_client -starttls smtp -showcerts -connect mail.example.com:587