My company has just taken over a smaller company and we are looking at our options for migrating there infrastructure into our domain.
Our domain is running 2008R2 and Exchange 2010 and we would like to migrate the newly acquired company onto our domain with as little downtime / user impact as possible.
The new company is running exchange 2003 in a 2003 domain, if I create a two way trust between both domains this will allow me to migrate AD users accounts security groups etc but I'm on unsure on the best strategy for migrating Exchange mailboxes from 2003 to exchange 2010. It would appear that Mailbox migration powershell commands are supported if exchange 2003 is on at least service pack 2 however if I take this method in order to migrate users does the move have to be a big bang migration ? or is it possible to do it as a staggered migration ?
I had originally thought I might have to upgrade exchange 2003 to exchange 2007 first and then migrate to exchange 2010 in the new domain is this a better plan if the migration is to be staggered ?