Does anyone know the case law for services that filter a person's mail for them? E.G if I employ a service that will open mail for me to weed out the junk and s

Does anyone know the case law for services that filter a person's mail for them? E.G if I employ a service that will open mail for me to weed out the junk and send me the good stuff, do my letters become business records? What if I also employ them to (going a step further), pay any bills that come in from my bank account? I think that this line has already been drawn. Tangential question: since the Supreme Court recently decided "do it with software" by itself is not sufficient (by itself) for software patents, can that precedent also be used for differentiating between letters and email? E.g. - letters with software is not enough distinction for 4th amendment bypass?