content: #!/usr/bin/env python
  """
  Create a directed graph, allowing multiple edges and self loops, from
  a unix mailbox.  The nodes are email addresses with links
  that point from the sender to the recievers.  The edge data
  is a Python email.Message object which contains all of
  the email message data. 
  
  This example shows the power of XDiGraph to hold edge data
  of arbitrary Python objects (in this case a list of email messages).
  
  By default, load the sample unix email mailbox called "unix_email.mbox".
  You can load your own mailbox by naming it on the command line, eg
  
  python unixemail.py /var/spool/mail/username
  
  """
  __author__ = """Aric Hagberg (hagberg@lanl.gov)"""
  #    Copyright (C) 2005 by 
  #    Aric Hagberg <hagberg@lanl.gov>
  #    Dan Schult <dschult@colgate.edu>
  #    Pieter Swart <swart@lanl.gov>
  #    All rights reserved.
  #    BSD license.
  
  import email
  from email.utils import getaddresses,parseaddr
  import mailbox
  import sys
  
  # unix mailbox recipe
  # see http://www.python.org/doc/current/lib/module-mailbox.html
  def msgfactory(fp):
      try:
          return email.message_from_file(fp)
      except email.Errors.MessageParseError:
          # Don't return None since that will stop the mailbox iterator
          return ''
  
  
  
  if __name__ == '__main__':
  
      import networkx as nx
      try: 
          import matplotlib.pyplot as plt
      except:
          pass
  
      if len(sys.argv)==1:
          filePath = "unix_email.mbox"
      else:
          filePath = sys.argv[1]
  
      mbox = mailbox.mbox(filePath, msgfactory) # parse unix mailbox
  
      G=nx.MultiDiGraph() # create empty graph
  
      # parse each messages and build graph 
      for msg in mbox: # msg is python email.Message.Message object
          (source_name,source_addr) = parseaddr(msg['From']) # sender
          # get all recipients
          # see http://www.python.org/doc/current/lib/module-email.Utils.html
          tos = msg.get_all('to', [])
          ccs = msg.get_all('cc', [])
          resent_tos = msg.get_all('resent-to', [])
          resent_ccs = msg.get_all('resent-cc', [])
          all_recipients = getaddresses(tos + ccs + resent_tos + resent_ccs)
          # now add the edges for this mail message
          for (target_name,target_addr) in all_recipients:
              G.add_edge(source_addr,target_addr,message=msg)  
  
      # print edges with message subject
      for (u,v,d) in G.edges_iter(data=True):
          print("From: %s To: %s Subject: %s"%(u,v,d['message']["Subject"]))
      
  
      try: # draw
          pos=nx.spring_layout(G,iterations=10)
          nx.draw(G,pos,node_size=0,alpha=0.4,edge_color='r',font_size=16)
          plt.savefig("unix_email.png")
          plt.show()
      except: # matplotlib not available
          pass
  