I have read about every paper on this, but to get it straight in my head. Client has a OWA server and one EXCH2003 server, the general upgrade process is: Prepare AD Extend AD Insert NEW CAS2007 server to Exchange system AT this time I assume both OWA and OA clients should be able to browse to either OWA or CAS server and login (correct?)? Redirect OA clients to new CAS2007 Insert New EXCH2007 Server(Mailbox & Hub Transport) Move Mailbox to EXCH2007 Redirect MAPI Clients to EXCH2007 Redirect incoming SMTP to EXCH2007 Decomission OWA Decomission old EXCH2003 - will this redirect my outbound SMTP I know i am condensing this but does it fit the flow? -- REMOVE X from Xname AND Xdomain to reply directly STOP SPAM

Hello This are the very common steps for Transition from Exchange 2003 to 2007 You can also follow this step by step method for migrating mailboxes first migrate some test mailboxes and check the outlook owa settings. Considering this you need to check the mail flow when migrating mailboxes. http://www.msexchange.org/tutorials/Transitioning-Exchange-2000-2003-Exchange-Server-2007-Part1.html http://support.microsoft.com/kb/555854 Thanks Mhussain

Hi, In addition to MMHussain. You can check all the transition articles. http://www.capslockassassin.com/wp-content/uploads/2009/09/Exchange_Server_2007_Transition_Guide.pdf http://exchangeserverinfo.com/2007/12/04/transition-from-exchange-2003-to-exchange-2007.aspx Thanks.

Hi, Here are some more good articles for you, Replacing Exchange 2003 Frontend OWA Server with Exchange Server 2007 Client Access Server: http://www.msexchange.org/articles_tutorials/exchange-server-2007/migration-deployment/replacing-exchange-2003-frontend-owa-server-exchange-server-2007-client-access-server.html Outlook Web Access and Exchange 2007, 2003 and 2000 Coexistence: http://msexchangeteam.com/archive/2007/02/07/434523.aspx Hope this helps. Best regards, SerenaPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.