As I mention when I send people info about payment, Payment is $33/30E for Advanced (20 Letters) or $50/45E for Premium (30 Letters)
With Advanced, if you email me, and I already have 55 customers to write for, you become the 56th I write for, while with Premium, you would be come the 1st I write for.
That is an example of how Premium would prioritize a customer in the line. Premium goes ahead of all the Advanced customers as they come in.