we are in the process of migrating from groupwise to exchange 2010. During the migration some users will be on groupwise and some on exchange. Our hardware internet gateway forwards all mails from the internet to a single ip address (our gw server).
We thought about pointing this hardware box to the new ex 2010 HT server as this one can forward all traffic for recepients - who are not on exchange yet - to the gw system. However, if something goes wrong we would loose emails.
The easiest solution would be a system which can decide based on the emails address (.txt file or something) were to route the email to.
Is there something which can to that and isn't too complicated to set up?