Open-Xchange. "Usage" section

The Usage page allows customers to view statistics on mailboxes usage by users attached to the Open-Xchange service.

To view the Usage page:

1. Sign in to the Customer Control Panel.
2. Hover the mouse pointer over the Mailboxes Entry Point. The  button is displayed in the lower right corner of the Entry Point.
3. Click . The Entry Point menu is displayed.
4. On the Entry Point menu, click Usage. The Usage table is displayed including the list of users’ emails attached to the Subscription, as well as the used space and quota for each email in the list.