Enable Port 25 On-Premise

I am running my own physical mail server on-site and port 25 is currently blocked. I need it opened and correctly routed so the server can both send and receive e-mails without relying on external relays. The job involves reviewing the router or firewall rules, coordinating any required changes with the ISP if necessary, and validating that SMTP traffic flows in and out once the port is accessible.

I will grant remote access (SSH or AnyDesk) to the machine and the edge device; after your work I expect to be able to run a Telnet test from outside the network, see the SMTP banner, and complete a full send/receive round-trip.

Deliverable: port 25 reachable from the internet with successful mail delivery tests and a brief log of the steps you took so I can replicate them if the hardware is ever replaced.