First click the magnifying glass next to the recipient you want to manage. This will bring up the manage window.
Next click the Site Alerts icon. This will bring up the Site Alerts window.
Now you can add alerts for actions that happen over the entire site for uploads, downloads, and disk usage.
Uploads: This alert is sent when any user uploads a file to the site.
Downloads: This alert is sent when any user downloads a file from the site.
Disk Usage: This alert is sent when the site exceeds 90% or more of its total allotted space.
Place checks in the boxes you with the recipient to get alerts for and click OK to save your changes.