Same issue for me !
I scheduled an email to go out on April 14, 2015 at 11:30am. it is now April 15, and the email did not go out. It was a time sentitive email as it should have gone out yesterday.
The schedule date was set correctly and the "send" button was clicked on April 10, 2015.
The emailing is now pending in the outbox (what prooves I clicked on the "send" button) but it doesn't seems to be sent (statistics = 0 sent ! )
Please get back to me ASAP !!