[Exim] (revised) Reverse DNS failures

Revised:

I know it is a stupid question, but I am experiencing a mental block.

My exim configuration is denying all hosts that do not have a Reverse DNS
set up (as expected). My problem is that there IS one host that I do want
to accept. How do you exclude one host from the reverse lookup?

Thank You
Terry Shows
terry.shows@???

Great thing about Email Spell-checker, is it doesn't know that the wrong
word is used, it only knows if it is spelled right. Sorry for the incorrect
post