Of course there are regulations on mailing potentially infectious bodily fluids: http://pe.usps.com/text/pub52/pub52c3_023.htm Having said that, a quick search of "mail in STD test" shows the market is flooded with competition. Probably why Aube is willing to sell his company. A LOI is classic bullshit in the penny world and vigil has no money to buy a company. Even if she did, she doesn't pay bills and gets evicted often.