There are a variety of ports used for accessing email protocols, most mail clients will select the right option automatically when you select the "Use TLS/SSL" or "Use Encryption" option, but if you need to select ports manually then the information below will help.
POP3
110 - Insecure default port, but secure with TLS/STARTTLS 995 - Legacy port for use with SSL
IMAP
143 - Insecure default port, but secure with TLS/STARTTLS 993 - Legacy port for use with SSL
SMTP
25 - Insecure default port, but secure with TLS/STARTTLS 465 - Legacy port for use with SSL 587 - Insecure alternative port, but secure with TLS/STARTTLS
