==== Provide required information to help troubleshoot and get quick answer ====
- Linux/BSD distribution name and version:
- iRedMail version and backend (LDAP/MySQL):
- Any related log? Log is helpful for troubleshooting.
====

Hi I have just installed the latest version of iRedAmin-Pro and I was trying to configure postfix in order to let users from my networks (e.g. 192.168.0.0/16) to send emails via smtp.
Those users do not have an account, they have their mail clients set with "smtp.mydomain.com". The point is that, in a normal environment I would go into the /etc/postfix/main.cf file and add those networks, but... (and this is the question):

should I simply modify the main.cf file or it will be overwritten next time I change somethingin iRedAdmin?
is there any other file for "manual customization" or I can simply start modifying that file?

I have this doubt because I see that something changed the main.cf file so I was wondering if I should keep it as it is and put some customization in some $includeme file.

Thank you