Exchange Online
To get started, Configure Exchange Online.
Exchange Online integration lets you create mailboxes when an Account entitlement is granted in Azure AD.
A mailbox is created when an account's Account entitlement is granted. The mailbox is shown in the address list when the account's Account Access entitlement is granted, and hidden from the address list when revoked.
Note
Licensing must be configured separately (for example, by using group memberships).