There are some definite advantages of using postcards as direct mail. You can measure the effect of the mailing by how many replies you receive. According to Larry Mersereau’s book, Post Card Power, (Promo Power, 2004), "And, the lowly post card can be the foot-soldier of your direct mail program. They’re inexpensive, easy to put together, and they put your message right where you want it: right in your prospect’s hands.