I have been sending notes to every deviant who's stock I like because I am developing a new body of works. I want to sell them on eBay, and if you have sent me a note and I sent you another one, it's because a couple of people have written back saying they already gave me approval and the note never arrived in my inbox for whatever reason.
I will absolutely respect your terms of service and I will not use your stock if either I don't hear from you, or you don't allow people to make paintings from your stock and sell them. I always change the picture and add so many original elements that I really don't need to ask for permission in most cases. Still, I want the clearance to make sure I don't ruffle any feathers.