Mail server

aaP_newbieKiller

is there any other way to use mail server without port 25?

aaP_pwawrzen

If you host on your server nope you need to specify port withone will be listen mail server.
If you use outsite mail server it's not your job how it works.

phxwolf

You can use a Mail Reflector or Alternate-port SMTP both are offered by No-IP