I don't know how really run Zentyal with Zarafa.
But Active Directory is the Microsoft LDAP version of LDAP. With my attached file we can alter Active Directory LDAP Schema.
With this schema update, integration of Zarafa is easier
You can easily exclude groups or users, can also easily define alias or define who can be send as for an email account. And many other things.
Outside Samba you must also alter the Microsoft active directory to install Zarafa or MS Exchange. Without it you can not get the necessary AD attributes to manage Mail Interfaces in RSAT.
Thanks for your link this is a temporary solutions.
Beckynet