[icebraining]

I have no data, but I bet you're an exception. People read emails when they get to work (yes, even personal emails); by sending them at 8:30, they get the email to reach people when they're already at their desk or at least at the top of the queue (since emails clients sort from newer to older).

If they sent it sooner, by the time people sat down and opened their inboxes, the email would already have been "submerged" under a bunch of others sent afterwards.