[Exim] How to test sender_reject

I would like to reject almost all of a domain.

     For instance, I would like to reject all of aol except for one nice
     person.

     I was thinking something like this would be correct:

     sender_reject = ! nice@??? : aol.com

     But I can't figure how to test it.

     I have tried

     exim -bt -f bad@???

     with delivery to a local user, but it is always accepted.
     It is accepted even for:

     sender_reject = *

     What is the correct way to test this setting?  Am I using it
     correctly or is there a better way?

     Thanks,
          Michael