Create a mailbox. With this approach, you create mailboxes in your %BRAND_OFFICE_365_SHORT% organization for users in your ...

Create a mailbox. With this approach, you create mailboxes in your %BRAND_OFFICE_365_SHORT% organization for users in your on-premises %BRAND_EXCHANGE_ONLINE_SHORT% organization. These mailboxes are called remote mailboxes and they are included in the on-premises Active Directory. Active Directory synchronization automatically synchronizes this new mail user object to the %BRAND_OFFICE_365_SHORT% service, which then converts it to an %BRAND_OFFICE_365_SHORT% user mailbox. See steps.