Is port 110 still used today?

Legacy systems still support it, but modern email clients strongly favor POP3S (Port 995) or IMAPS (Port 993) to protect credentials with TLS encryption.

What is the difference between POP3 (110) and IMAP (143)?

POP3 downloads emails to a single device and removes them from the server, while IMAP synchronizes folders and read states across multiple devices simultaneously.

How do I test port 110 reachability?

Check reachability using our Open Port Checker tool or execute 'nc -zv mail.example.com 110'.

Home/Open Port Checker/Port 110

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Well-Known Port Reference

Port 110: POP3 (Post Office Protocol v3) (TCP)

Post Office Protocol version 3 used by email clients to retrieve messages from a remote mail server.

Port Number

110

Transport

TCP

Security Risk

High

Standard / RFC

RFC 1939

Test Port 110 Reachability Live

Verify whether Port 110 is open, closed, or filtered on your server or public IP address.

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Service Architecture & Function

Port 110 is the traditional unencrypted port for POP3 email retrieval. In standard POP3 operation, an email client connects to port 110, downloads all pending emails to local storage, and optionally deletes them from the remote server.

Security Profile & Hardening

Cleartext passwords and message bodies are transmitted without encryption on port 110. Security best practices dictate migrating to encrypted POP3S on port 995 or IMAPS on port 993.

Example Firewall Commands:

# UFW (Ubuntu/Debian)

sudo ufw allow 110/tcp

# iptables (Direct Kernel)

iptables -A INPUT -p tcp --dport 110 -j ACCEPT