So let me see if I understand this. Alice gives me a letter, and asks me to read it and to give it to Bob. (We are all three parties to it.) The government, wishing to investigate Alice or Bob, can serve me a warrant for the letter, and demand all other of my papers that I have relating to the two? And I have no standing to contest the warrant, because it's served "against" Alice and Bob even though it's going after papers that are in my possession and of interest to me?
Is this what the Framers meant by "papers" in the phrase "Persons, Papers and Effects"?