kerio control was setup years ago as the mail server. In 2003, then 2007 they upgraded to exchange, leaving kerio as the "gateway". So email comes in through Kerio, filtered on viruses and spam then if the mailbox doesn't live in kerio it is forwarded to mail.company.com. That is where exchange 2007 currently lives with all the roles on one server. Now is where it gets interested. I have joined the company and my first task is to upgrade to exchange 2010 and move the company to a new domain. I currently have 2 new domain controllers setup with the new domain with a trust relationship between it and the old domain. I also have Exchange 2010 installed in a 2 server setup (1 with edge transport, the other with hub transport, mailbox and client access). I made a few test users and have migrated them successfully from the old domain to the new and moved the mailbox as well. My main problem is getting mail to work happily in the current setup until it is complete then I remove Kerio Control and just have the edge transport server on the frontlines. I don't have a problem with eliminated Kerio Control right away and that might be the best solution but im having troubles pinpointing if it is possible to have two exchange, in different domains work nicely together so employees in both domains can get email directed towards them during the switch.

It is defintely possible for both environments to coexisit. Your options are 1. Make kerio changes to accept email for both 2007 and 2010. If Kerio is intelligent enough to roue to 2007 and 2010 or send everything to 2007 and send it 2010 via internal relay. 2. Replac kerio with edge and have edge deliver the email.

I think you can follow this document to configure in your enviroment: Configure Exchange 2010 to Route Messages for a Shared Address Space http://technet.microsoft.com/en-us/library/bb676395.aspx Thanks, EvanEvan Liu TechNet Community Support