I am having an issue with a migration were the environment is 2003 with two front end servers and two mailbox servers that are managed thru veritas clustering. When we try to setup the coexistance to access the users 2003 mailbox from the exchange 2010 front end no matter what dns changes I make or what script I run you cant access those mailboxes. This is huge as it has now delayed my migration by 5 days and I need to come up with a resolution. I was curious as to if anyone has run into this issue and what the fix was?Preston Thornhill

You can't use an Exchange 2010 CAS to get to an Exchange 2003 mailbox server regardless of what cluster solution you're using. You can't do it without a cluster either. All an Exchange 2010 CAS will do to get to an Exchange 2003 mailbox is redirect the request to the Exchange 2003 front-end server. Except for ActiveSync--Exchange 2010 will proxy ActiveSync requests, and I doubt that Veritas clustering would make any difference with that either.Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."

Ok so I worded it badley. Yes I understand that they connect to the front end servers on the Exchange 2003 side but I justed to be sure there is no known issues with this? ThanksPreston Thornhill

There are a number of things you must do to make this work properly. Not having any background on what you've done or how you've set it up, I can't begin to diagnose your issue. You are welcome to follow this document and see if your set-up is consistent. http://technet.microsoft.com/en-us/library/ee332348.aspxEd Crowley MVP "There are seldom good technological solutions to behavioral problems."