Test your server SSL using OpenSSL cli
HTTPS openssl s_client -connect mail.yourserver.com:443 IMAPS openssl s_client -connect mail.yourserver.com:993 POP3S openssl s_client -connect mail.yourserver.com:995 POP3 TLS openssl s_client -connect mail.yourserver.com:110 -starttls pop3 IMAP TLS openssl s_client -connect mail.yourserver.com:143 -starttls imap SMTPS openssl s_client -connect mail.yourserver.com:465 SMTP TLS openssl s_client -connect mail.yourserver.com:587 -starttls smtp To show expired date of certificate add : | openssl x509 -noout -dates for example: openssl s_client -connect mail.yourserver.com:443 | openssl x509 -noout -dates