How to send mail via postfix?

Question

postfix

How to set up sending mail if DNS is on zoneedit.com?

Answer 1

At a minimum, you need to make an additional MX record leading to your server or change the one that is registered there automatically (if you do not use it).
Further information is missing.

Answer 2

In the main.cf file, it is correct to set at least mynetworks:
mynetworks = 192.168.0.0/24 (add a subnet allowed for sending)
which will allow mail to be relayed from your subnet through your postfix.
and here dns - it is not clear.