Hi ivanv,
I think that is not possible. Zentyal is not made to be a true multidomain emailserver (true separate domains).
I use Zentyal for multidomain email server and I have the same problem. How I partial solved (disable shared Adressbook and Contacts):
Edit "sogo.conf.mas":
nano /usr/share/zentyal/stubs/openchange/sogo.conf.mas
Here, modify in "/* LDAP authentication */" from YES to NO, like here:
1. For ADRESSBOOK:
id = sambaShared;
displayName = "Shared Addressbook";
canAuthenticate = NO;
isAddressBook = NO;
2. For CONTACTS:
id = sambaContacts;
displayName = "Shared Contacts";
canAuthenticate = NO;
isAddressBook = NO;
After modifications, you must restart the service or the entire system.
Unfortunately, I don't know how to do this to be permanent (I understand that can be copied "sogo.conf.mas" in a special location and the modifications will be permanent, but ...).
If there are updates/upgrades for SOGO or Openchange, after they are applied, you must modify again sogo.conf.mas
Kind regards,
Gabriel