This is a complete total utter consummate waste of money– and the art world’s version of spam. You have no idea how the mailing list was assembled, what kinds of galleries these are, what kinds of art they deal in, whether your art is even remotely right for them, etc. etc. etc. Would you walk up to a total stranger and ask him to buy your art? That’s basically what you’re doing with galleries when you buy mailing lists. Galleries get these kinds of random intergalactic inquiries all the time. What makes you think they’re going to look at yours when they throw all the others in the trash?