If you have become a Captains Member or Crown & Anocher Member you will receive mailings etc etc for future cruises. The cruise lines also send out a coupon after every cruise, and these can only be used towards a future cruise with that cruise line. Neither of the Coupons can be used towards another cruise line - you can not use Captain Club coupons towards a Royal Caribbean Cruise and vice versa. However if your Travel agent may want to recongize these as a favour if you are a repeat client. Most of us in the travel industy like myself will recongize the coupons if the cruise lines wont.
***edited by moderator to remove commercial link***