I'm with Sprint, but received the same email (Sprints servers went to crap during the entire pre-order process). I was able to complete my order (Matte Black, 128gb, 7+) at 2pm yesterday and have an ETA of 10/4-10/10.
i was able to complete through ATT Friday morning for a 9/23-9/30 estimate.
Did the ATT chat and they reversed the upgrade flag so its available again.