about regexp syntax. To allow a .org sender, use
This would only affect smtpd_sender_restrictions (or, whatever restriction list the access table happened to be in), not the other checks; so, the message would still be subjected to header/body checks.
If you are rejecting a message based on certain header/body patterns, and yet you still find occasion to make exceptions in certain cases, then I suggest that those patterns should not be used as a basis for rejecting the message. header/body checks are meant to be an all or nothing thing.
Finally, see BUILTIN_FILTER_README.html#domain_except
under Configuring header/body checks for mail to some domains only
, which discusses setting up a second smtp listener with the checks turned off. But, I don't think that's what you had in mind.