@UncT 

Currently, Deco does not support DMZ functionality. However, you can replicate the DMZ effect by opening all ports for your mail server. To achieve this:

1. Open the Deco app
2. Go to More > Advanced > NAT Forwarding > Port Forwarding
3. Set both the internal and external ports to 1-65535
4. Select your mail server device

Important Note: Enabling this setting exposes the device to the Internet. Please make sure that a firewall is properly configured on your mail server, otherwise there might be security risks. Since this is a mail server, ensure you have appropriate security measures in place including strong authentication, updated software, and proper firewall rules on the server itself.

This configuration will effectively give your mail server the same exposure as a traditional DMZ setup, allowing all incoming traffic to reach it.

Thanks