I'm not sure I do understand your question but I'll do my best to provide some insight:
- All the Servers in your CRM 2011 deployment must be in the same Active Directory domain. But your CRM 4.0 and CRM 2011 deployments can be in different domains.
- Users added to the Microsoft Dynamics CRM Organizations can come from different Active Directory domains or forests.
- Emails configuration can come from anywhere and doesn't need to rely on Active Directory. For example, you may wish to integrate with POP3 and SMTP servers for Incoming and Outgoing Emails. Those configurations must be done at the Email
Router level.
Hope this helps,
If you would like me to give more details on anything feel free to ask,
Maxime