From: Gecko on
Does anyone know if it is possible to reject mail from a sender
directly destined for one address on your domain and not the whole
domain.

So stop user-1(a)a-domain.co.uk sending mail to user-1(a)b-domain.co.uk
but not stop user-1(a)a-domain.co.uk to the rest of users on the @b-
domain.co.uk ?

Thanks.