Move permit_mynetworks to smtpd_relay_restrictions in default master.cf.in

[Maksim Usmanov <skamasle@gmail.com>]

Hi everyone,

I'm trying to add a check_policy_service to Postfix using
smtpd_recipient_restrictions, but I found a small limitation in the
default PMG template (master.cf.in).

Right now, the template has this:
-o smtpd_recipient_restrictions=permit_mynetworks,reject_unauth_destination

With this setup, it's hard to add a policy service safely because it
needs to go after those two options to avoid relay issues.

I know I can use a custom template, but maybe it makes sense to change
the default one? If we move permit_mynetworks to
smtpd_relay_restrictions as the Postfix docs suggest here:
https://www.postfix.org/postconf.5.html#smtpd_relay_restrictions , it
would be much easier to add custom checks or policy services later.

Is there a specific reason to keep the current structure, or could we
update it to follow Postfix recommendations and make it more flexible?

Thanks for your help!

Best regards,

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Att: Maksim