Hello, I've installed Exchange 2007 in a new forest. I raised the functional level of all my domains to W2K3, but forgot to raise the forest functional level (it's still W2K). I have about 5000 users and mailboxes in 5 child domains, and the system is nowlive and critical for my users. The workstations are all in another forest and will be migrated later. Is there any warning / known problems about raising the forest level from W2K to W2K3 after installing Exchange 2007 ? Thanks for your feedback. Gerald.