Change the setting in the Calendar application
For security reason I have port 25 closed for all unix users and open for all cpanel users.
In webmail, horde for example, I have modify the port from 25 to 587 in the configuration file and it's works fine (587 it's open).
Calendar application send the email (for example if you share event) with localhost:25 and is not possibile to change this settings. I want to change this setting with localhost:587