[1] : Jargon File (4.3.1, 29 Jun 2001)

paper-net n. hackish way of referring to the postal service,
   analogizing it to a very slow, low-reliability network. usenet sig
   blocks sometimes include a "paper-net:" header just before the sender's
   postal address; common variants of this are "papernet" and "p-net". note
   that the standard netiquette guidelines discourage this practice as a
   waste of bandwidth, since netters are quite unlikely to casually use
   postal addresses. compare voice-net, snail-mail, p-mail.


see also:
sig block netiquette voice-net snail-mail p-mail 

[2] : The Free On-line Dictionary of Computing (27 SEP 03)

paper-net
     
        snail mail
     
     
see also:
snail mail 

Paper-Net >> P Words
Paper-Net, definition of term: Paper-Net
paper-net_pag1.html