How to Block outgoing SMTP Mail from all but one Computer

In this example we will show how to configure the firewall in a Vigor2820 router to block outgoing SMTP mail from all computers but allow mail to be sent from one computer (mail server) with a static IP address of 192.168.1.10

Step 1 – Filter Setup

Go to Firewall >> Filter Setup configuration menu.

Select “Default Data Filter” and then select then next filter rule to edit as shown in the diagram below:

Step 2 – Edit Filter Setup

1. Enable Filter rule
2. Select direction LAN to WAN
3. Enter IP address of computer to be allowed to send SMTP mail then invert selection as shown in the diagram
4. Set destination IP to “ANY”
5. Set Service type to use:
   1. Protocol TCP
   2. Source port ANY (1 – 65535)
   3. Destination Port  25
6. In “Application” set Action to Block immediately