Official List

Comonly used Email Port Numbers

The following are the most frequently used well known port numbers for email communications or used by mail servers.
Port Number Protocol
25 TCP SMTP Mail Server (for sending outgoing emails)
110 TCP POP3 (for receiving email)
119 TCP NNTP (Network News Transfer Protocol)
143 TCP IMAP4 Protocol (for email service)
465 TCP Secure SMTP (email) using SSL
993 TCP Secure IMAP protocol over SSL (for emails)


Gmail Ports

Port TCP/UDP Service
995 TCP Incoming POP3 mail server
465 TCP Outgoing SMTP Mail server (SSL Port )
587 TCP Outgoing SMTP Mail Server (TLS/Start TLS Port)