Reminder Emails

How can we manually\automatically push out event reminders to the attendees prior to the event?  We did find the listing of our attendees and you can do this individually, but we couldn't see a way to do this on an entire group scale.

For example - we open the event.  We want to send out an email to all attendees 3 days before the event, and another email at 7am on the morning of the event.