Postfix master.cf edit help

NethServer Version: 6.8
Module: mail
I would like to edit master.cf I do not know what template to edit. Will someone please help me. My outcome should be this:

smtp      unix  -       -       n       -       -       smtp
    -o syslog_name=default
    -o smtp_bind_address=1.2.3.4.5
    -o smtp_helo_name=server1.example.com

When I send emails through my Nethserver the ip address shows up as my gateway (modem) address and not the ip address of the NethServer. A dirty way would be to use smtp_bind_address.

Did you already test this configuration? Are you sure it would solve your issue?

Maybe I didnt understand the problem, but I guess the postfix SMTP client can’t bind to an IP address that is not assigned to a network interface.

BTW for helo there already exists a specific prop. Please see

http://docs.nethserver.org/en/v6.8/mail.html#custom-helo