Hello, I am migrating from exchange 2007 to exchange 2010 and I am currently in Coexistasnce Mode. If connect via Outlook web access to a 2010 mailbox and then attempt to use the Open Other Mailbx to open an exchange 2007 mailbox I receive the following error: The custom error module does not recognize this error. The URL that I am redirected to is: https://e2007.exchange.mycorp.com/owa/auth/logon.aspx?url=https://e2007.exchange.mycorp.com/owa/postmaster@mycorp.com/&reason=3 If I start with a fresh session and attempt to connect to the 2007 mailbox that works. I am redirected to the 2007 CAS. Thanks Bill

Hi, OWA 2010 can only open the mailboxes in exchange 2010 mailbox database. If you try to open an additional mailbox which is in exchange 2007 through OWA 2007, you will be redirected to OWA 2007. Gen Lin TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com

Hi, Uest that is exactly what I would expect. Unfortunately itstead of getting the OWA 2007 Page I get this: A blank white screen: with the following text: The custom error module does not recognize this error. Bill