Port 110 (POP3) — What It Is and How to Use It

Port 110 is the standard port for the Post Office Protocol version 3 (POP3), a protocol used by email clients to retrieve email from a mail server. It allows users to download emails to their local devices, typically deleting them from the server afterwards, although options exist to leave them on the server.

Last updated: 2026-03-02

                Port Number
                110
            

Protocol POP3

Common Use Cases

Downloading email from a mail server to an email client (e.g., Outlook, Thunderbird).
Accessing email on devices with limited storage by downloading and deleting emails.
Retrieving email in environments where persistent server storage is not desired.

Check if Port 110 is Open

netstat -tulnp | grep :110

Get-NetTCPConnection | Where-Object {$_.LocalPort -eq 110}

⚠️ Security Note: POP3 transmits usernames and passwords in plaintext by default, making it vulnerable to eavesdropping. Consider using the secure version, POP3S (Port 995), which encrypts the connection with SSL/TLS.

Related Ports

Frequently Asked Questions

Is port 110 dangerous to leave open?

Leaving port 110 open without proper security measures (like using POP3S or restricting access) can be dangerous. Attackers could potentially intercept usernames and passwords, gaining unauthorized access to email accounts. It's recommended to disable POP3 if not needed or to use POP3S (port 995) instead.

What service uses port 110?

The service that uses port 110 is the Post Office Protocol version 3 (POP3) server. This service listens for incoming connections from email clients requesting to download email messages.