You can send all your cards through them for both stateside and overseas and they handle incoming and outgoing QSL's. Print your call sign in the upper left hand corner. DX stations include enough IRC's for each envelope. I will give you the address in a minute where to send them so have a pen and paper ready. To send your QSL cards through the bureau, arrange the cards alphabetically by call sign.
Stateside cards are free.
All cards outside the U.S. postal districts are 10 cents each. If you change your call sign, keep the bureau informed. They will also mark each envelope you send them so you will know how many envelopes are left. All mailings are at the end of the month. If you want your envelope sent to you only when there are so many cards in the envelope, immediately below your call sign in the upper left corner, indicate how many cards you desire before mailing to you.