Coupons by zip code

[gourmetdelights]

I like to offer US Military serving overseas a coupon for 10% off their order. Since they may be new to my website, they wouldn't know of this coupon a priori. Thus I need to list it for everyone to see. I've done this.

HOWEVER I find people are abusing that coupon. It is meant only for AP/AE addresses but I'm finding people using it for any of the 50 states. I honor it but would like to restrict the coupon to only AP/AE addresses.

Thanks.