Hello - hopefully I can explain my situation clearly. Currently we have one Exchange 2003 server on a single domain, single forest AD network. We will be transitioning to a new server - Exchange 2007 very soon. My problem is that our company is physically moving it's office and in the new bldg. we will have another company (or two) leasing office space. The first tenant company wants to contract services with us where we will host their email on our server. They will have their own AD Network, DC and file server, but they don't want to handle their own Exchange server. I expect the two networks to be connected with a domain trust and be separated via firewall rules or VLAN. They have their own email FQDN and can change the MX record accordingly. I have no idea how to structure this from a networking perspect or whether Exchange 2007 can support this. I'd geatly appeciate any direction or comments on how to accomplish this or if it's even possible or advisable. Thanks! Ted

I'm looking for the same information. Any takers on this?

If there is a domain trust than this is going to be possible. Basically what you would be doing is you would be using your Exchange environment as a resource forest for them. Generally you would create a user account on your domain for each of those users (either manually or automatically using directory synchronization). The next step would be to grant their user accounts access to the users mailboxes on your server. In addition you'd need a new recipient policy in Exchange and your DNS/SMTP routing is going to need to be configured to support mail for their domain. Take some time reviewing Resource Forest designs before you jump in. Good luck, Erik