You must deploy an Active Directory synchronization server to synchronize mail-enabled Active Directory objects to your %BRAND_OFFICE_365_SHORT% ...

You must deploy an Active Directory synchronization server to synchronize mail-enabled Active Directory objects to your %BRAND_OFFICE_365_SHORT% organization. This synchronization server supports a unified global address list (GAL) between your on-premises %BRAND_EXCHANGE_ONLINE_SHORT% and %BRAND_OFFICE_365_SHORT% organization.