I booked a flight on delta.com last night (one-way on DL metal). As of this afternoon, I still haven't gotten an email confirmation. What's more, I pulled up my booking on delta.com and requested that the receipt be emailed (twice, each time to a different email address hosted on a different domain), and I still have not received it.

What is interesting is that I did get the "Your Upgraded Seat" email this morning, so that's working for me, but the email confirmations are not.