Today on their blog, the Exchange Team announced that with the latest Exchange 2013 Cumulative Update 8 and Exchange 2010 SP3 Rollup Update 9 that a new feature is included to improve the experience for ActiveSync devices when migrating to Office 365. The problem has always been that users had to manually make changes to their ActiveSync device post Office 365 migration to get it connected to Office 365. Now with the new feature an ActiveSync device will be able to determine that the mailbox has been moved and re-point to Office 365 much like the full Outlook client does.

Read more about this here (Not sure why the pictures are not showing up)