Odd behaviour - marketpress sending order notifications to wrong email but only on one site

I was just made aware of an odd bug or perhaps it's a setting somewhere that I'm totally missing.
I have a bunch of MU subsites using marketpress and one of them recently had a change in the email address of the user.

Marketpress is still sending the order notifications to the old email address and the current main user isn't receiving them.

Where would I go or what can I do to figure this one out? I'm totally stumped!

Thanks for any help you can give me!