Installing your first Exchange 2010 CAS – Part 3
This is the third, and last, part of the "Installing your first Exchange 2010 CAS" tutorial. In part 1 we discussed migration from Exchange 2003 to Exchange 2010, In part 2 migration from Exchange 2007 to 2010. Today we will discuss the case of mixed Exchange 2003 - 2007 environment.
If you managed to get your Exchange 2003/2007 environment working together then you already know that Exchange 2007 CAS can proxy requests to Exchange 2003 mailbox servers. We also know from part 1 of this tutorial that it is not the case for Exchange 2010.
Right now you have your Exchange 2007 CAS that is internet facing and handling all incoming requests by itself. Basically you should think of this as a combination of part 1 and part 2, one thing is common and it is that the newly introduced Exchange 2010 CAS will be dealing with incoming requests.
For Exchange 2007 Mailboxes
Bug revealed in Dynamic Distribution Groups on Exchange 2007
I have been lately involved in a question on Experts-Exchange that turned into a very interesting adventure that led me to discover a bug in the Dynamic Distribution Groups on Exchange 2007.
I have tested the below on Exchange 2007 SP2 rollup 2 and the bug was still there, however I need to mention that tests also proved it was solved on Exchange 2010.
The Setup
First let me give you a very brief idea about the setup, for the lab I have setup an EBS server and created 2 mailboxes on it "John Doe" and "Jane Jackson".
Running Get-Recipient shows the 3 mailboxes in this organization

Taking a look at Active Directory Users and Computers also reveals that "John Doe" and "Jane Jackson" are located in the TestOu, the Administrator is located in the Users containter

The Plot
Allow relaying on Exchange 2007 & Exchange 2010 in 4 easy steps
I have this application/website that needs to send emails, I have it configured to use our exchange server as SMTP. It can send emails to internal users however external ones are failing with a "550 5.7.1 Unable to relay" error
I have been answering this question, under different forms, so often on Experts Exchange lately that I have it copied on a notepad and end up by pasting it again every now and then.
First a mail server should be configure to unconditionally (not talking about spam/viruses here) accept emails sent to users in the smtp domains it serves. However it should be careful about who gets to send emails to other smtp domains using its services, that's what is called relaying.
This should explain why, in the above scenario, emails sent to internal users are received but not to external one. So for your application to be able to send external emails you should allow it (or its IP address) to relay emails through your exchange server and here is how to do it in Exchange 2007 and Exchange 2010.
Installing your first Exchange 2010 CAS – Part 2
A few days back I have talked about Installing your first Exchange 2010 Client Access Server when migrating from Exchange 2003 to Exchange 2010. Today I will discuss the requirements of installing your first Exchange 2010 CAS if migrating from Exchange 2007.
First we have to agree that that an Exchange 2010 CAS cannot communicate directly with an Exchange 2007 mailbox servers, so Exchange 2007 CAS are still required.
We will need to differentiate 2 scenarios when mixing Exchange 2007 & Exchange 2010 CAS
Exchange 2010 CAS and Exchange 2007 CAS in the same Active Directory Site
The first Exchange 2010 CAS server should be installed in your internet facing site, and it should be the first server people are directed to when they try to access your organization from the internet using, say, https://webmail.yourdomain.com/owa
Since Exchange 2010 Client Access Server cannot proxy the requests to an Exchange 2007 CAS server in the same active directory site, when the request reaches the 2010 CAS it will query Active Directory for the mailbox server of the user, if that mailbox is located on an Exchange 2007 mailbox server in the same Active Directory site the CAS will look for the ExternalURL & InternalURL parameter of that CAS server.
26 things I shouldn’t forget about Exchange 2010 DAG, nor should you!
I am currently involved in planning and designing a couple of site resilient Microsoft Exchange 2010 clusters so I have been reviewing my notes and here is one I would like to share with you.
In short it is the summary of an 11 pages long technet document in 26 points I had previously highlighted on papers.
Installing your first Exchange 2010 CAS or the truth about Exchange2003Url – Part 1
The Exchange2003Url is a new parameter in the Set-OwaVirtualDirectory cmdlet on Exchange 2010. Although Microsoft documentation clearly states that "The Exchange2003Url parameter specifies the Outlook Web App URL for Exchange 2003 mailboxes." It is all over the net that this parameter is also used to redirect requests to Exchange 2007 mailboxes!
I have no idea where this idea is coming from but I can assure you that is not the case.
Upgrading from Exchange 2003 to Exchange 2010
If you are upgrading from exchange 2003 you should know that an Exchange 2010 CAS cannot communicate directly with an Exchange 2003 mailbox. Thus you will need to publish at least 2 URLs one for your Exchange 2010 CAS and one for you Exchange 2003 Back End server or Front End server.
We will assume that https://owa.yourdomain.com/owa will point you to your exchange 2010 CAS server and https://ex2k3.yourdomain.com/exchange will give you access to your exchange 2003 back end or front end server.
By running, on your Exchange 2010 server,

