What is the product code for the Pistol?
I know you bought an M&P so expect you are talking about S&W's rebate of extra magazines and not a Print Magazine. I expect they need to know which pistol it is for, then they will select the appropriate magazine to send you.
S&W is currently offering 2 Mags or a $50 rebate for purchasing a M&P semi auto. I can choose the mag
capacity on the form. Would they send the 17 round versions to a state that only permits 10 rounds?