Hi This question may have been covered before, so apolgies in advance. I have 4 E2K3 Bridgeheads split between 2 different sites that have connectors to all other E2K3 Mailbox servers globally. These 4 boxes are 32-bit. If I install E2K7 Mailbox servers into this environment, can I use the E2K3 Bridgeheads for mail routing or do I need to replace/augment them with E2K7 Hub Transport servers? Obviously to avoid the initial purchase of more 64-bit server for the Hub Transport role, I would like to use the E2K3 Bridgeheads in coexistence and look at replacing the old 32-bit boxes further down the track. Does anyone have any experience of this?

http://technet.microsoft.com/en-us/library/bb124350.aspx

Thanks for that, I have read that article before. What I was really after is someone withfirst hand experience of a migration,as reports are ambiguous. Some sources say replace all E2K3 Bridgeheads with E2K7 Hub Transport servers prior to installing an E2K7 Mailbox server. Another book (E2K7 Unleased I think) mentions that you don't have to replace 'all' your E2K3 Bridgeheads, so long as you have at least on routing group connector between sites. Does that mean 1 E2K7 Hub Transport server or none??