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,
After migrating to Lync 2010 server some of my client users where not able to log in using OCS 2007 R2 clients due an incompatibility in the Authentication Service version.
I have checked the OCS 2007 R2 client logs, by browsing to %userprofile%\tracing\Communicator-uccapi-0.uccapilog and noticed the following error
010/08/2010|11:51:55.781 E0C:14A8 INFO :: SIP/2.0 401 Unauthorized
We are all faced, from time to time, with the need to change the IP address of our Microsoft Exchange server.
There is no hard relation between the operation of your Exchange server and its IP address thus changing the latter will not break your system.
In short this operation can be considered as safe however it requires a certain level of planning and considerations. I will try to cover in this article the various things you should think about before and after actually changing the IP of your server.