I can see that a user can get an alert for low disk space and that you can set an email notification for overall free disk space is less than %.
However, what would be more logical would be an email notification where C: falls below a value (say 3GB), rather than the overall or individual drives and at a percentage.
Is this possible? As Admin's its important to have an alert like this, rather than a scheduled report that you need to look at every time it runs.