response = server.retr(msgCount)
msg = email.message_from_bytes(b'\n'.join(response[1])
for part in msg.walk():
    print(part.get_content_type())
    if part.get_content_maintype() == 'multipart':
        continue
    if part.get('Content-Disposition') is None:
        print("no content dispo")
        continue
    filename = part.get_filename()
    
    fp = open(os.path.join(self.savedir, filename), 'wb')
    fp.write(part.get_payload(decode=1))
    fp.close

import pickle
f = open('msg.dat', 'rb')
response = pickle.load(f)
f.close()

>>> import pickle
>>> import email
>>> 
>>> r = pickle.load(open('msg.dat', 'rb'))
>>> 
>>> m = email.message_from_bytes(b'\n'.join(r[1]))
>>> p = tuple(m.walk())[-1]
>>> n = p.get_filename()
>>> c = p.get_payload(decode=True)
>>> 
>>> n, c[:10]
('LSN_00003396_T6.lsn', b'\x0c\x00\x00\x00Nemesi')
>>>