Port 110: POP3
Download email from a server, unencrypted.
- Port
- 110
- Protocol
- TCP
- Service
- POP3
- Exposure
- Do not expose to the internet
What is port 110 used for?
Older mail clients.
Is it safe to expose port 110 to the internet?
Use POP3S on 995 instead, or move to IMAP over TLS.
If port 110 seems closed or unreachable
- Check that the POP3 service is running and listening on port 110, not only on 127.0.0.1.
- Check the firewall on the host itself (Windows Defender Firewall, iptables, nftables, ufw) for a rule that allows TCP 110.
- If the host is behind a router, confirm the forwarding rule points to the correct internal address and that your internet provider does not use carrier-grade NAT.
- Test from outside your own network. A port can be open locally and blocked at the edge, or the other way round.
Using port 110 safely
Treat port 110 as an internal-only service. Reach it through a VPN or an SSH tunnel, restrict it by source address, and keep the software that listens on it patched.
Check whether port 110 is open on your host
The check connects from our server, so it shows what the internet can reach.
Open the port checker