Alphabetical order makes sense to me. My initial is B (for bastard) and they tried to take my payment Monday, and sent the email on Tuesday.
They would get all the applications on the system before taking payments and putting tickets aside, otherwise they'd have no idea about the numbers for each price band and how many tickets in each price band would be available to put aside for those who went to buy in person. So it makes perfect sense that once they knew how many tickets they needed to hold back for form applicants they'd then work through the list alphabetically off their computer database to distribute the tickets, any other method would be messy and tedious.