What are the conditions for opening port 25?
I need a mail server to use the email authentication function in the service I am developing.
And I developing groupware for our employees to use.
Among them, there is a webmail function, and I think it is necessary to send and receive mail.
However, I issued a ticket requesting the opening of port 25 and received a reply from the staff that I could not open it.
Please check the conditions required to open port 25.