hi there,
i am not very experienced in linux (in fact i can set up a running system).
I have to set up a linux system between a firewall and a complex system of viruswall, spammbox and mailserver. The only thing the linux machine has to do is checking the inbound smtp stream:
if the recipient is not listed as an employee than the connection has to be terminated (or the mail deleted). If the recipient is listed than the mail has to be forwarded to the next station. The list of the employees can be a text list or (that would be the perfect) from the already running ldap server.

can anyone give me some clues to do this?

thanks in advance