Port 110 is used for the POP3 (Post Office Protocol version 3) email protocol. It is commonly used for receiving email from a mail server.
Ports those registered with IANA are shown as official ports. The same port number may be unofficialy used by various services or applications. The official usage are listed separately below its usage may change from time to time.
Official
| Port | Protocol (TCP/UDP) | Title | Description | Port Type |
| Port 110 | tcp | pop3 | Post Office Protocol Version | WELL KNOWN PORT |
| Port 110 | udp | pop3 | Post Office Protocol Version | WELL KNOWN PORT |
UnOfficial
Unofficialy or sometimes with conflict, the same port may be used by different applications.
| Port | Protocol (TCP/UDP) | Description |