When you view the Users page of the Office 365 portal in Microsoft Office 365, you receive the following message:
One or more users need an assigned license in order to retain an Exchange Online mailbox. Create a new view and select “Users with mailboxes and no licenses.” Select all users in the list, and then click “Edit” to assign licenses.
Additionally, you experience the following symptoms:
Exchange Online licenses are missing for users who were created in the Exchange admin center or in Exchange Online PowerShell.
Sudden mailbox loss for users who were created in the Exchange admin center or Exchange Online PowerShell.
This occurs if the user mailboxes are created in the Exchange admin center, and the users aren't yet assigned a license.
Create a view in the Office 365 portal to display a list of users who have mailboxes but who don't have a license. To do this, follow these steps:
Click users and groups, and then click active users.
Click Filter (), and then in the drop-down box, click Unlicensed users.
Note To assign a license to a user, double-click the user. On the "Assign licenses" page, click to select the check boxes next to the items that you want to assign, and then click save .
Users must be assigned a license, or the mailbox is deleted. From the time that the user mailbox is created in the Exchange admin center, admins have 60 days to assign the user a license in the Office 365 portal.