Hi Folks, we currently have an old Exchange 2000 mail server that is groaning under the weight of it's age. We are looking to create a new setup based on 2007 and are a little confused about all the server roles that seem to be needed. We have only a few specs: Based on 5 years growth we are looking at: Max 500 users 1Gb max mailbox per user 2 sites with replication/redundancy access via Outlook, webmail and windows mobile ability for any one site machine room to die and the other site pick up the load Is such a setup possible and how many boxes would be needed? From my (poor) understanding of the way Exchange 2007 works we need 4 boxes per site for Mailbox Server, Hub Server, Client Access Server and Edge Server. What spec would people recommend these boxes take? Is there a set of recommendations per user or similar? How (if?) does the replication work if a site fails? Thanks for any pointers

Gordon, First thing to remember with E2K7 is that you must run it on 64-bit hardware. So, you will likely be investing in new hardware for each server that you will need to deploy. I don't have a lot of experience with the failover portion of E2K7 yet, but here are some links that you can read. The good news is that there are now a lot of options for failover with 2K7, some of which do not call for shared, expensive, storage: http://technet.microsoft.com/en-us/library/bb124721.aspx You can set up replication between the mailbox servers in your 2 sites. For the rest of the roles... Edge Transport is not required. If you already have an anti-spam/anti-virus gateway in place, you don't have to put in the Edge Transport. It is a nice add-on, but not required.The Edge Transport MUST run on it's own hardware. It cannot share any roles with other servers. There must be at least 1 hub transport in each of your sites that has a mailbox server. E2K7 uses AD sites to make routing decisions so each site that has a mailbox server must also have a transport hub. So, if you have mailbox servers in each of your 2 sites, you will need a hub transport in each. You only have to have a single CAS to provide client access to external devices. If you want a CAS in each data center, then you will obviously need 2. If you have an issue with hardware costs, you can combine CAS and HUB on the same server. For specs on the servers, check this: http://msexchangeteam.com/archive/2007/01/16/432222.aspx