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How to Block Port 25




If you are emailing from your VPS/dedicated server and you need us to raise the packets per second limit on port 25 for your VPS, reply back to us and let us know.

If you are not emailing from your VPS/dedicated server , you may find that you want to block access to port 25. This can help prevent spam from being sent from your server.

The steps may very slightly depending on the Linux distro that you are using, however the general steps will be the same. In this example we will use CentOS.

Step 1: Add iptables rules to Drop port 25

iptables -A INPUT -p tcp --dport 25 -j DROP
iptables -A OUTPUT -p tcp --dport 25 -j DROP

Step 2: Save iptables rules

service iptables save

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