We currently have two sites running independently, Exchange and Domain Controller at each site. There is a VPN link between the two sites. The two sites run different domain names but we'd like everyone at both sites to have the same email domain.
We'd like to move everything in to one Exchange but keep coming up with different ideas how to achieve this. What would be the fastest and most cost effective way to achieve this as any downtime on either Exchange will have to be done at the weekend.