Accepting tickets or CC users not in Active Directory

Fixed my last issue but here is one I am unsure about.

I am using LDAP authentication and it works great.

I need to also be able to accept tickets from or send replies to people who
are not in AD. They do not need to be able to view their tickets, only the
email correspondance.

Thoughts?

Vance Walsh
Network and Systems Administrator
Concord Academy - Concord, Mass.