Beginning with Exchange Server 2010 SP3 RU9, Exchange Server 2013 CU8, and Exchange Server 2016, a new MobileSyncRedirectBypass feature was introduced in the Autodiscover service for Android devices.
By default, this feature is enabled for devices that have the following prefixes:
Note The MobileSyncRedirectBypass feature is generally known as "451 redirect." For more information, see 18.104.22.168.2 HTTP Error 451.
- Manually edit the server value for the Exchange ActiveSync (EAS) profile after the mailbox is moved to Office 365.
- Test to determine whether the device supports the MobileSyncRedirectBypass feature. If the device supports the feature, edit the MobileSyncRedirectBypassClientPrefixes setting across all Exchange servers in the environment.