[exim] Stopping Internal Email Abuse

Hi guys,



Hopefully this email makes the rounds!



I've had a request from the MD to try and stop the amount of junk that gets
sent around each day by employees.



I need internal email to work to 2 or 3 addresses, so I was thinking a
time-based blacklist perhaps.



Basically, chris@internal must not be able to email *@internal, apart from
the one or two allowed addresses such as accounts@ or production@.



I'm using Exim4, has anyone done this sort of thing already, or anyone able
to point me in the right direction?



Regards,



Chris