参考：
https://github.com/python/cpython/blob/2.7/Lib/imaplib.py
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from socket import *
s = socket(AF_INET, SOCK_STREAM)
s.connect(("imap.163.com", 143))
'''
'HZ1 CAPABILITY \r\n'
'HZ2 ID ("name" "com.tencent.foxmail" "version" "1.2" "vendor" "Tencent Limited" "contact" "[email protected]")\r\n'
'HZ3 LOGIN "[email protected]" "huzhi567233"\r\n'
'HZ4 LIST "" *\r\n'
'HZ5 SELECT "INBOX"\r\n'
'HZ6 FETCH 1:* (UID)\r\n'
'HZ7 UID FETCH 1392612616 (UID BODY.PEEK[])\r\n'
'''
cmd = 'HZ1 CAPABILITY \r\n'
print cmd
s.sendall(cmd)
data = s.recv(10240)
print 'Received:', repr(data)
s.close()参考：
https://github.com/python/cpython/blob/2.7/Lib/poplib.py
#!/usr/bin/env python
# -*- coding: utf-8 -*-
from socket import *
s = socket(AF_INET, SOCK_STREAM)
s.connect(("pop.163.com", 110))
'''
'USER [email protected]\r\n'
'PASS huzhi567233\r\n'
'STAT\r\n'
'LIST\r\n'
'RETR 15\r\n'
'''
cmd = 'USER [email protected]\r\n'
print cmd
s.sendall(cmd)
data = s.recv(10240)
print 'Received:', repr(data)
s.close()