With an Exchange-based hybrid deployment, you can choose to either move on-premises Exchange mailboxes to the Exchange Online organization or move Exchange Online mailboxes to the Exchange organization. When you move mailboxes between the on-premises and Exchange Online organizations, you use migration batches to perform the remote mailbox move request. This approach allows you to move existing mailboxes instead of creating new user mailboxes and importing user information. This approach is different than migrating user mailboxes from an on-premises Exchange organization to Exchange Online as part of a complete Exchange migration to the cloud.
The mailbox moves discussed in this topic are part of administrative Exchange management in a longer-term coexistence relationship between on-premises Exchange and Exchange Online organizations.
Ganesan, Sr. Technology specialist.