[Exim] host_reject_recipients and SMTP AUTH

Hi folks,

I'm using host_reject_recipients to block certain sites, and the default
behavior for Exim is to block mail from sites that don't have reverse DNS
properly configured.

I like that, and want to leave it that way, except for one thing. I'd like
to allow connections from machines that have properly authenticated.

Is there anything like "+allow_unknown", maybe "+allow_auth"?

Mark