This tool will send users email based on how they have subscribed to
dashboards. A dashboard is a set of saved searches, the subscription controls
how often that dashboard is sent and how it's displayed.
Each subscription has an hour, and possibly day of week or day of month. These
are taken to be in the user's timezone if available, UTC otherwise.
You'll need to have cron run this script every hour. Here's an example crontab
entry to do this.