Introducing Exchange 2010 into Exchange 2003 Environment, need some quick insight regarding message flow

Posted on 2011-09-27
Last Modified: 2012-05-12
In the existing Exchange 2003 environment there are 2 servers.  A mailbox server and a front-end server.  The mailbox server receives inbound mail via a SonicWall appliance, which receives it from the Internet.  The mailbox server is configured as the bridgehead server and is configured to forward all mail through the outbound connector to the smarthost, which is the front-end server.  The front-end server hosts OWA, which is the primary email access method for over 500 of our users.  

Here's my question:  I am about to introduce Exchange 2010 into this environment and I want to know specifically how this is going to interfere with the current mailflow and at what point in the installation?  Because of the time involved in creating/modifying DNS records, mx records, firewall rules, etc I need to be certain of these mailflow changes.  Will mailflow change as soon as I introduce CAS into the environment on the 2010 box?  Will 2003 want to start routing mail out through 2010 CAS?  If so, I'll need to change rules on the SonicWall.  Can I leave my inbound mail rules as they are and will 2003 automatically route inbound mail to 2010 if the mailbox is a 2010 mailbox?  Or do I need to change inbound mail rules for SonicWall to point to 2010 CAS instead of 2003?

Idealy I'd like to have both 2003 and 2010 working simultaneously and to have OWA for both working at the same time as well.

Please advise?
Question by:wpstech
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Expert Comment

ID: 36713589
When you introduce the new 2010 server to the 2003 environment, you shouldn't have mail flow issues right away.  The first thing to do is to check public folder replication (after you set it up).  if that's all clear then you move a mailbox and test mail flow from that test mail box.  If this is a single server deployment, the mail serer where the mailboxes sit should still be your Front end server.  tYou won't need to change your NAT rules until you move your mailboxes.  You should have to change external DNS unless you decide to change you OWA URL.  

Author Comment

ID: 36716347
I am planning to introduce 2 new 2010 servers into the existing 2003 environment.  I am planning to have CAS, HT and MBX roles on both new servers.  Soon after both 2003 (MBX and FE) will be removed.  My plan was to change the OWA URL and add a 2nd MX record to external DNS so that both OWA URL's (2010 and 2003) would be available.  Does this all sound alright?  Please clarify the inbound/outbound mailflow in my scenario after I introduce 1st and 2nd 2010 server.  I want to better understand the route that mail will flow inbound/outbound between these 4 (2-2003, 2-2010) Exchange servers running in a mixed environment.  

Author Comment

ID: 36716481
also, for the two 2010 servers that will be a DAG and both will host active mailboxes, how does OWA work with this?  I'm assuming that OWA will be setup w/ the same URL on both servers and Exchange will just know which server to route to when a request comes in from a user accessing their mailbox via OWA
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Accepted Solution

SuperTaco earned 300 total points
ID: 36716599
DAG is usually just for the mailbox data.  to be able to have mailboxes on both sevrer and keep the saem URL you will have to set up a redirect.  thismight have some answers

Author Comment

ID: 36717712
thanks, i came across part two of that article and between both parts it does answer a lot of the questions I had regarding the mailflow during coexistence and the routing of requests from an OWA perspective.  

Once I have both new 2010 servers in place and have the DAG setup and CAS array setup and I have active mailbox databases on both of the new servers, how does OWA work?  Do I have to setup OWA twice (once on each server)?  Can you point me to something that would describe the configuration/access to OWA with muliple mailbox servers and with a CAS array between the same 2 servers?  I will either be using a hardware NLB or I will not load balance, as I know that CAS array and DAG cannot co-exist on same servers if also wanting to load balance.
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Expert Comment

ID: 36717932
Correct.  Honesltly I haven't set up a DAG yet,  You can do failover through your firewall if you have an ASA, not sure about a SonciwALL, but I imagine you should be able to.  

See i this helps

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