If you read the Subscription Management/Preference center guides here and elsewhere, the recommendation isUnsubscribed=Email Opt OutEmail Opt In=separate field(s)
I just spoke with my team member and they said that you must still offer the asset even w/o opt in checked.Again, I'd spend some time with legal if you plan to follow such a model.
First, I'm not a lawyer. Best to discuss with legal counsel.That being said, I would agree with them - if you want to get the content, you must check the box. For a Contact Us form...
In addition to what Greg said:All emails must have a footer allowing an Opt Out/Unsubscribe. So I while you could say that line, I would ADD it to all of your emails through May 24...