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

Hi Bill Did you get anywhere with this problem. I am just testing co-existence now, and get similar problems. I am testing domain.co.uk redirecting to legacydomain.co.uk.... In terms of OWA connections, redirections works fine. But, if i log into OWA 2010 and then try to open a 2007 users mailbox OR Inbox OR Calendar, it doesnt work. Perhaps if you could get in touch we can assist one another with other issues. Tom Tom

Hello, I did not ever get this to work. I simply acclerated our migration and finished it as rapidly as possible to avoid the issue as much as possible. I'm sorry for the late response. I haven't been very active in the forums lately. Bill