Port 25 is used by Simple Mail Transfer Protocol (SMTP). Email transmission between mail servers. Port 25 is for server-to-server mail delivery.
What Does an Open Port 25 Mean?
A mail server is accepting inbound email. Port 25 should only be open on mail servers. On end-user devices or non-mail servers, an open port 25 may indicate malware.
This port should NOT be open to the public internet on typical systems. If you see it open, investigate immediately.
Security Risk Level
Medium Risk
How to Check if Port 25 Is Open
Use the ExamineIP Port Scanner to check if port 25 is open on any IP address from the public internet. Enter the target IP and select the relevant port preset.
How to Close Port 25
- Stop the service using port 25 if you no longer need it
- Add a firewall rule blocking inbound connections on port 25
- Check your router for port forwarding rules that expose this port
- Run
netstat -ano | findstr :25(Windows) to see which process is using it
Related Ports
SMTP is related to: {implode(‘, ‘, Array)}
Protect Your Open Ports
If you need services like remote access, use a VPN to create a private encrypted tunnel instead of exposing ports directly to the internet. A VPN also hides your real IP address so port scanners cannot identify your device. Try PureVPN or IPVanish.