There are some persons, I don't want to sent automatic replies to, how do I do that?

This may be a bit tricky/messy, as you have to find an attribute for storing the unwelcome remote address first. In case you don't feel like extending LDAP schema (and updating all objects in the database), I suggest, you simply (ab)use the vacationForward attribute for this. Then adapt the queryfilter to something like:
"( &(&(mail=$receiver)(vacationActive=TRUE))(!(vacationForward=$sender)) )"