Port 110POP3
Post Office Protocol version 3 (POP3) is a widely used email retrieval protocol designed to allow email clients to download messages from a mail server for local storage and offline access. Operating on TCP port 110, POP3 facilitates the transfer of emails from the server to the client, emphasizing simplicity and minimal server-side resource use..
- transport
- tcp
- in transit
- cleartext
- assignment
- official
- risk
- 4/10
- lookups
- 15,517
single transport
payload readable on path
registered with iana
caution
rank 203 of 993 · top 20%
Technical Details
what runs on :110POP3 is an application-layer protocol defined in RFC 1939 that enables email clients to connect to a remote server and retrieve email messages. It primarily operates in a pull-fashion, meaning clients initiate connections to check and download emails. POP3 sessions begin with user authentication followed by a series of commands that allow listing, retrieving, and deleting messages from the server.
Typically, once messages are downloaded via POP3, they are removed from the server unless configured otherwise. This design choice supports offline access and minimizes storage on the server, but it limits email synchronization across multiple devices. Unlike IMAP, which supports complex mailbox management and server-side storage, POP3 focuses on straightforward download and local retention.
POP3 communications occur over plaintext by default, resulting in unencrypted transmission of credentials and data. To enhance security, POP3 over SSL/TLS (commonly on port 995) is recommended. Despite the rise of more feature-rich protocols, POP3 remains relevant due to its simplicity and client support.
Security Information
exposure of :110risk score
4/ 10caution
worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.
email averages 3.9 across 42 ports — this one sits 0.1 above.
in transit
cleartext
credentials and payloads are readable by anyone on path
assignment
official
registered with iana for this service — scanners fingerprint it by number
reachable over
tcp
every listening transport is another surface to filter at the edge
security overview
Common Vulnerabilities:
- Credentials transmitted in plaintext susceptible to interception (Man-in-the-Middle attacks).
- Lack of encryption exposes email content during transit.
- Susceptible to brute-force password attacks if strong authentication controls aren’t enforced.
- Potential exposure to buffer overflow vulnerabilities in poorly implemented POP3 servers.
Common Mitigations:
- Use POP3S (POP3 over SSL/TLS) to encrypt traffic and protect credentials.
- Enforce strong password policies and implement account lockout mechanisms to reduce brute force risk.
- Restrict access to trusted networks or through VPNs.
- Keep server software regularly patched to avoid exploitation of known vulnerabilities.
- Consider deploying firewalls or intrusion prevention systems to monitor and limit POP3 activity.
Related Ports
the 8 most looked-up other ports in email — 42 ports carry that label.
| port | service | risk | |||
|---|---|---|---|---|---|
| :143 | IMAP | TCPUDP | caution | 20.7k | |
| :995 | POP3S | TCPtls | caution | 18.8k | |
| :109 | POP2 | TCP | caution | 17.9k | |
| :2096 | cPanel SSL Webmail | TCPtls | Web Services | safe | 17.4k |
| :993 | IMAPS | TCPtls | caution | 14.5k | |
| :1352 | Lotus Notes RPC | TCP | caution | 12.3k | |
| :24 | Private Mail | TCPUDP | caution | 11.7k | |
| :7025 | Zimbra LMTP | TCP | caution | 11.4k |
risk mix of the 8 listed
- safe13%
- caution88%
3 of 8 encrypted