We setup a Stalwart application for mail server and followed the Stalwart documentation to setup the server application.

Everything worked great until we make a troubleshoot of the emails delivering, where we found that emails was not being delivered due to a port timeout issue on port 25.

However, the port 25 is already configured in a domain in the Project Settings.

Project ID: a8915625-d504-49f4-9cd2-e6aefaa4ad2c
Screenshots of the setup is attached.

How could we solve this issue?