Greetings!  We recently placed our Exchange 2010 environment in a hybrid state with O365.  I am using two Exchange 2013 servers as hybrid servers.  Autodiscover, OWA, EWS, etc all point to the Exchange 2013 hybrid servers.  Microsoft connectivity tests all pass for both on premise and O365.

As part of my test plan, I set up a test account and then configured email for this account on a windows phone, in Outlook and in Windows 8.1 mail app (activesync).  After I finalized the migration batch, I got the expected notification in Outlook.  After re-launching Outlook, my account settings were properly updated.  For the Windows 8.1 mail app, it also updated the settings.  However, on the windows phone it is giving an error about trying to contact our on premise Exchange 2010 CAS which leads me to believe it is not redirecting properly and updating the account settings. 

I have not tested with any iPhone or Android device yet.  My understanding from reading various articles is that Windows Phone and newer versions of iOS should redirect with little issue, whereas there are known issues with Android devices.  I am thus confused why this device is running into a problem.

Thanks in advance for any advice/assistance.

I came across the following statement on this forum guide:
http://www.msexchange.org/articles-tutorials/office-365/exchange-online/configuring-exchange-2013-hybrid-deployment-and-migrating-office-365-exchange-online-part16.html

Exchange ActiveSync

"When dealing with mailbox moves from Exchange on-premises to Exchange Online, the Exchange ActiveSync client will not be able to automatically update the ActiveSync profile via the autodiscover redirect to Exchange Online. The profile must be reconfigured manually. This is true for all ActiveSync client types (Windows Phone, iPhone, Android etc.)."

Can anyone confirm this statement?  I am getting conflicting information on this point.  From my testing, it would seem that activesync clients are *not* updating, at least not phones.  I tested with an iPhone6 and it also did not update the settings for the user account; he had to manually update the mail server, then everything worked.