Bypass restrictions for postmaster/abuse

[MRob]

Hello all,

Is there a best practices for exempting the postmaster/abuse address 
from certain smtpd_mumble_restrictions?

For example, we see some small businesses who have trouble getting past 
reject_unknown_helo_hostname and reject_unknown_client_hostname and if 
we reach out to them, we need to allow their reply to our postmaster 
address to get delivered, obviously bypassing the checks that originally 
caused the rejections.

I think each organization will have restrictions that they deem 
important enough to place even before exemptions for postmaster, but I'd 
like to learn what other Postfix administrators have done, how they've 
done it, and if there is commonly agreed upon way to approach this.

Thank you!