In the recent issue of JSNT 31.3(2009): 279-299, Peter Head has an article on named letter-carriers among the Oxyrhynchus papyri.
"This paper analyses the role played by named letter-carriers among Greek personal letters in the Oxyrhynchus papyri as possible background for Pauline practice, and within the context of recent proposals concerning the role of the letter-carriers within Pauline practice. Around forty letters are discussed, with three examples analysed in more depth (P.Oxy. 113; P.Oxy. 3313; P.Oxy. 3505). It is seen that, when named and identified within the letter, the letter-carrier frequently supplements the written communication with some oral supplement. Against some recent proposals no evidence is found in support of the view that the letter-carrier ever read the letter itself to the recipient."