- Port
- 110
- Protocol used by the service
- TCP
- IANA registrations
- TCP/UDP
- Encryption
- Unencrypted
- IANA description
- Post Office Protocol - Version 3
- IANA service name
- pop3
Note: IANA has formally registered POP3 on TCP/UDP, but in real-world practice this service operates over TCP only — a formal registration on a transport doesn't guarantee the protocol is actually implemented or used over it. This page's Protocol field reflects genuine usage, not just the registry entry.
What port 110 is used for
Downloading email from a mail server to a single client, typically removing it from the server afterward — an older model than IMAP's server-side, multi-device synchronization.
Is port 110 encrypted?
Not encrypted by default on this port; the encrypted variant (POP3S) runs on port 995 instead.
Firewall & exposure considerations
Largely superseded by IMAP for anyone using more than one device to check mail; still supported by most mail servers for compatibility with older clients.
Related ports
References
Look up any other port
Search the full IANA registry — all 6,100+ ports and 12,500+ protocol-specific records — on the Port Lookup tool.
Last reviewed: . Data source: IANA Service Name and Transport Protocol Port Number Registry. Security and usage notes are this site's own editorial content, not official IANA data.