Creating a consent form for people to sign. Collecting a few details in and then asking if people don't mind to be sent a few details in the future via email.
Bearing in mind they will have a pen in their hand, and will be filling in a few details (and obviously I want them to allow me to send information) would it be better to write...
"Please tick this box if you do not want to be contacted in the future"
"Please tick this box if you don't mind being contacted occasionally"
"By leaving this box blank you are agreeing for your details to be used in this way"
That make sense? My wife has confused me...