The entire issue of UCE is being debated by the United States Congress and the European Union as well as various national, state and local legislatures.
New legislation is put forward on an almost daily basis.
It is not likely that there will be a satisfactory definition of, let alone a solution for, the issues surrounding UCE anytime soon. If it is your desire to pursue this line of discussion, I suggest you consult a legal expert. Putting the political and legal debates aside for the moment, I contend that UCE is a waste of the web promoters resources. This is not usually the type of first impression that most of us want to make with our potential customers. There are several ways to do this, but the most common is the opt-in mailing list.