Hosting multiple email domains for receive and send, within a single AD?

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Ginger Monkey

I know that historically this is effectively a non-starter, but was wondering if it had changed.

Outline situation is a company with two distinct brands, but who want to be able to operate from single premises and on a single IT platform. To support this we need to be able to set things up such that each user has:
one AD log on one Outlook profile can receive email to both and can have a default send address defined on either a or b can manually override the default for specific messages (or even better, have Outlook reply with the appropriate From address based on the To address of the incoming message)

I know I could achieve the desired result by running Company B on its own LAN, with a DC + Exchange box, and then use Outlook 2010 for the clients, and condense the multiple Exchange accounts down (although I'm not sure what that would do for things like Calendar and Contacts integration), but it would be preferable to use the kit we'd need to do that to provide redunancy on a combined/integrated approach, if that can be done now.

Does that make sense? If so, is it possible in 2010?

Ed Crowley [MVP]

You can have the first three easily. The last two are tough. When you send mail with MAPI, you send with the " reply" address, i.e., the one that's bolded with the capital SMTP in the mailbox properties. The only way to do this has been to create two mailboxes or to use a POP or IMAP client that sends with SMTP, letting the user choose the from address. Or, creating two mailboxes, one for each identity, and having the user switch between them, or use Outlook for one and OWA for the other. Now, Outlook 2010 allows you to open more than one MAPI mailbox at a time, so that might be an answer, but I'm not familiar enough with that new feature to be able to give you guidance, sorry.Ed Crowley MVP " There are seldom good technological solutions to behavioral problems."


Setup multiple mailboxes/users for each person (,, ...) Which ever account is the master (one they log in with) needs to have full access to the other mailboxes. Forward slave account emails to master using delivery options in Exchange. Can setup the default send by setting that user to use it as master account or via outlook profile.

I have a similar setup, main issue in Outlook if the user wants to send email as a slave account they must change the " From" field when composing the email. I'm sure there is a way around it but never spent time looking into it. Most of the users need to login and send 90% of their emails using the master account domain, a few only log in and send with secondary domains because that is who they work for and do not have access to the other company files. In Exchange I have separate DBs based on company structure.
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