What port does POP3 use?
POP3 uses 110 and 995, and which one depends on what you are doing.
The older mail retrieval protocol, in plain and TLS forms.
| Port | Protocol | Name | What it is for |
|---|---|---|---|
| 110 | TCP | POP3 | Mail retrieval that downloads and usually deletes messages from the server. |
| 995 | TCP | POP3S | POP3 over TLS. |
Exposing it
Unencrypted. Use port 995 (POP3S), or better, IMAP over TLS on 993.
Checking it is listening
sudo lsof -i :110 # macOS, Linux
netstat -ano | findstr :110 # Windows
nc -zv host 110 # from elsewhereAn "address already in use" error on a port nothing appears to be holding usually means the socket is in TIME_WAIT rather than that a process has it — the ports reference covers that and the ephemeral range.
Frequently asked questions
What port does POP3 use?
POP3 uses ports 110, 995, and they do different jobs. 110: Mail retrieval that downloads and usually deletes messages from the server. 995: POP3 over TLS.
Is port 110 safe to expose to the internet?
Unencrypted. Use port 995 (POP3S), or better, IMAP over TLS on 993.
How do I check whether POP3 is listening?
sudo lsof -i :110 on macOS or Linux, netstat -ano | findstr :110 on Windows. From another machine, nc -zv host 110 says whether anything answers.
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Port 110 in full · Port 995 in full · Every service · All port numbers