Isolating email users from intenet

Hi all:

Some of our customers want to isolate some groups of users 's email: this groups can send and receive email only to/from the intranet (company domain) not from the Internet.

I was thinking use mappings but I wonder about the use of ldap attributes to acomplish this.

For example mailUserStatus and InetUserStatus, if I disable the last one, will I get this kind of isolating?

Any kind of sugestion will really appreciated.!!

[480 byte] By [705234] at [2007-11-25 8:49:55]