Feature request: show and allow disabling automatically trusted local subnets

[Covalenco_S]

Hello,

I am running Proxmox Mail Gateway 9.1.0 with two network interfaces:

ens192 public-address.240/24
ens224 192.168.10.240/24

Under Configuration > Mail Proxy > Networks, I configured only explicit /32 trusted hosts. The public /24 subnet is not displayed in the GUI and is not present in /etc/pmg/mynetworks.

However, the generated Postfix configuration contains the entire directly connected public subnet:

postfix.mynetworks = 127.0.0.0/8 192.168.10.250/32 ... public-address.0/24 ... [::1]/128

The subnet appears to be derived automatically from the PMG interface configuration.

I understand that this is currently documented behavior and that directly connected networks are automatically trusted for the internal SMTP port. I also understand that it can be overridden by maintaining a custom /etc/pmg/templates/main.cf.in.

However, the effective trusted subnet is not visible in the PMG GUI. An administrator reviewing Configuration > Mail Proxy > Networks may therefore assume that only the explicitly listed /32 hosts are trusted.

Could PMG provide the following options?

1. Display automatically generated trusted networks in the GUI as read-only entries.
2. Add an option to disable automatic trust of directly connected subnets.
3. Allow administrators to use only explicitly configured trusted hosts without overriding the complete main.cf.in template.
4. Show a warning when the internal SMTP port is reachable through a public-addressed interface.

Maintaining a complete custom Postfix template only to remove one implicit subnet also requires comparing the custom template after every PMG update.

Is there currently a supported PMG 9 method to disable the automatically added subnet while continuing to manage explicit trusted hosts through the GUI?

Thank you.