[exim] deny specific senders to a specific address

Hello,

I want to reject all mails from a group of local senders in a file +
from all external
domains which are addressed to a specific address to be bounsed back to the
sender with a meaningfull message.

for an example,

joe@??? and jenny@??? should be able to send emails to
global@??? while all other local user's and external
domain emails which
the destination is global@??? will be bounsed back to the respective
sender.

is this possible? if so, could somebody pass me a sample rule to put in my Exim
config, it would be very much appreciated, because i'm having a
serious issue with
my exim server.


Thanks a lot,

--
vk.