You must create the service account to associate with the service account all your user mailbox accounts that require protection.

Note: To create user mailboxes in Exchange 2016, refer https://technet.microsoft.com/en-us/library/jj991919(v=exchg.160).aspx.To create user mailboxes in Exchange 2013, refer https://technet.microsoft.com/en-IN/library/jj991919(v=exchg.150).aspx.

Procedure

  1. Log in to your Office 365 as an administrator.
  2. Navigate to Office 365 admin center > USERS > Active Users.
  3. To add a new user, select the "+" icon. The create new user account page appears.
  4. On the create new user account page, complete the required information.
    1. Enter the first name, last name, display name, user name, and your email domain.
    2. Select Type password and enter the password for the service account.
    3. Deselect the Make this person change their password the next time they sign in check box.
    4. Enter the email address of the recipient to whom the password must be sent. Select Create.
    5. Select Close.
    An Office 365 license is assigned to the service account. The service account does not require an Office 365 license to be assigned to it. You can remove the assigned license by editing the license.
  5. Select your service account from the Active users list.
  6. Select Edit next to the Assigned License. The Assigned License page appears.
  7. Deselect the check box for the assigned license. Select Save.