Thank you Bill,
This is the part I missed:
> Anyone can make their domain point to your MTA as a
> backup MX.
And my postfix will automatically act as backup MX for anyone who simply
adds my ip as back MX unless I set "permit_mx_backup_networks".
Now it is clear
On 2021-05-04 at 20:38:55 UTC-0400 (Wed, 5 May 2021 03:38:55 +0300)
IL Ka
is rumored to have said:
Hello,
It is suggested to provide list of relay_domains explicitly for the
backup
mx:
http://www.postfix.org/STANDARD_CONFIGURATION_README.html#backup
But another solution is to set "permit_mx
