... > If we do not hear from you, we will assume that you have no objection.
So, they will claim that, by not responding, the recipient agreed. Some jurisdictions I am aware of accept verbal contracts or this kind of written contracts, since civil proceedings will not be held up to a high standard of proof. Even then, there must have been evidence of a contractual agreement, ie. no response = no agreement. I say the lawyers are now working to prove that no response means the potential recipient agreed. If this email has been caught by enough spam filters, they will claim the majority agreed.