Mail App with LDAP Users not showing in TO field

We are not able to get the Mail app to auto-suggest any of our LDAP users. The LDAP users all show up in Settings/Users and they show up in auto-suggest style in Talk, Deck, Calendar, and Files. The LDAP groups/mailing lists do show up in the Mail app however. Anyone else with an LDAP authentication able to see their LDAP users from the To field in Mail?