Exchange On-Premise to Office 365: Flawless ActiveSync Migration
Microsoft has found a new way to migrate and update active sync URL when we migrate from on premise to office 365.
All on premise migration has always been flawless but when we used to migrate to office 365, we had required to update the active sync device manually if dns pointing to on premise.
With the newly released Exchange 2013 CU8 and Exchange 2010 SP3 RU9, it is possible to update the active sync device with the new URL of office 365.
This is how it works now.
Migrate the mailbox from on premise to office 365.
ActiveSync device tries to sync using the currently configured URL which connects to on-premises Client Access server. This can be Exchange 2010 or 2013 CAS.
This Client Access server further queries Domain controller to check if the user mailbox is present.
Then Client Access server gets a response from Domain controller that the user mailbox is not found.
Then Client Access server queries to find the “TargetOWAURL” attribute present on the organization relationship object for the Office 365configuration.
The “RemoteRoutingAddress” attribute present on the remote mailbox which is used to find the correct organization relationship.
So here Client Access server receives the TargetOWAURL configured on the Organization Relationship.
Now Client Access server sends the URL in an HTTP 451 response to the mobile device. Device should support HTTP 451 redirection.
The active sync device tries to sync with the new URL.
The active sync profile on the device is updated to the Office 365 URL.
More information about this change can be found here.
Let us know more about these 2 attributes.
The TargetOwaURL parameter specifies the Microsoft Office Outlook Web App URL of the external organization defined in the organization relationship. It is used for Outlook Web App redirection in a cross-premise Exchange scenario. Configuring this attribute enables users in the organization to use their current Outlook Web App URL to access Outlook Web App in the external organization.
Now ActiveSync migration process also use the same url to connect to your office 365.
The RemoteRoutingAddress parameter specifies the SMTP address of the mailbox in the service that this user is associated with.
If you’ve configured mail flow between the on-premises organization and the service, you don’t need to specify this parameter. The remote routing address is calculated automatically. “RemoreRoutingAddress” is a “TargetAddress” Attribute configured on an on premise mail enabled user.
I hope this helps in the understanding this change.
Microsoft MVP | Exchange Server