SSL versus TLS versus STARTTLS
http://sial.org/howto/openssl/tls-name/
The following are common ports used by e-mail, web, and directory services.
smtp 25/tcp Simple Mail Transfer
http 80/tcp World Wide Web HTTP
pop3 110/tcp Post Office Protocol - Version 3
imap 143/tcp Internet Message Access Protocol
ldap 389/tcp Lightweight Directory Access Protocol
https 443/tcp http protocol over TLS
smtps 465/tcp #smtp protocol over TLS (was ssmtp)
submission 587/tcp Submission for Simple Mail Transfer
ldaps 636/tcp sldap #ldap protocol over TLS
imaps 993/tcp # imap4 protocol over TLS
pop3s 995/tcp # pop3 protocol over TLS