I'm looking for some guidance on server roles as I look to deploy Exch2007. I have a limited budget for this and can only get 2 servers for my environment. I already have an AV/Anti-Spam solution, so I don't think the Edge Transport is needed. I'm not interested in the UM role yet so that leaves that one out as well. Should I combine the Client Access and Hub Transport on one server? This way, I can set up send and receive connectors for smtp messages to external destinations, controlthe outgoing disclaimeras well as giving access to remote clients. Similar to an FE server in Exch2003. Should I then put a combination of Hub Transport and Mailbox on the second server? With this, I can create internal policies for things like journaling and capture, as well as storing the mailboxes. Any thoughts on this would be appreciated. R

split roles on 2 servers is OK, I would probably go for MB on one server and CAS/HUB combined on another server, this will give you most value of your hardware. You can design those servers different, MB role needs many different disks and more RAM. But it all depends on how much load users put on your servers. if you dont have that many users you can combine all roles on the same box, but spreading roles out to different hardware gives you more flexibility

another thing, if you installed Two Hub Servers under single AD Site, then these servers are load balanced by default, if any of the hub servers failed the other takes over immidiately. by this you are providing load balanced for the mail flow process under your exchange environment. but, as lasse says, if you have heavy type of users who uses big attachments and send and recieve emails too much, then you have to seperate the MBX Server role on a different hardware, and keep your HUB/CAS Server on the other server. it depends on your size of your organization and how critical is your mail system.

I've read that the Hub Transport is the server that handles all of the policies that guide where the mail goes, and how it might be appended, blocked, copied, journaled,etc. To have these policies implemented, does every message have to pass through a Hub Transport? For example:If we want to use advanced journaling, then every message has to pass through a Hub, even messages between users on the same MB server, right? That's the reason behind my thinking of using 2 Hubs so that messages don't have to leave the MB server if internal policies are being used. Also, if the CAS is installed on a different subnet than the MB server (ex: web dmz), what ports need to be opened through the firewall for the communication to properly flow between the servers. Thanks.

All mail pass through HUB server regardless of what you like it or not, even if you send a mail to your self. Exchange is designed this way. If you have multiple HUB servers in the same AD site, Exchange will loadbalance mail between them. In each AD site that has a mailbox role installed you also must have a CAS and a HUB server role. Dont put CAS in a DMZ, your firewall will look like fishnet when you're done. Use a reverse proxy instead. ISA is a good choise for this.