Short legal questions are rarely as simple as they appear. Accepting by a check box (opting in instead of opting out) increases the chance of enforceability. If the opt in is at the bottom of the terms, even better. I am not licensed in your state, which may have special laws on contracts of "adhesion" (take it or leave it agreements between parties of unequal bargaining power) so local advice beyond my analysis may be required.
Answered on Jun 26th, 2012 at 2:06 PM