Greetings! I have a lab set up at home where I have been testing co-existence of Exchange 2013 and 2010 for a future corporate upgrade project.
I am running into some odd behavior. Any mailbox that has been migrated to Exchange 2013 works just fine, however, when I try to set up Outlook for a mailbox still on Exchange 2010 I receive errors. OWA works just fine for these Exchange
2010 mailboxes, it is just Outlook that has the problem. This is what I am running into:
1. Outlook uses autodiscover to locate server settings. It fails at the 'logging on to mail server' step saying that Exchange isn't available; Outlook must be connected, etc.
2. It then gives me the settings box for Exchange server and Mailbox. This is auto populated with one of the Exchange 2013 servers (there are 3 of them, all have both MBX and CAS role). If I then change the server to the Exchange 2010 CAS server, and hit 'check names', it underlines the very same entries (like it found them this time) that were there initially and goes on to finish the configuration.
3. When I launch Outlook with this Exchange 2010 user, it fails to open with the error message that the set of folders couldn't be opened.
I've been doing as much research on this as I can. I've tried disabling IPv6 to no avail. It seems as if perhaps the issue is with Exchange 2013 proxying the request back to the Exchange 2010 servers but I am not sure what to check in that regards. Any suggestions? Thanks in advance!