Tutorial on using Python poplib module and smtplib module to send and receive emails

pp = poplib.POP3_SSL(host)

smtplib: Send SSL/TLS secure email using python
Python's smtplib provides a very convenient way to send emails. It simply encapsulates the SMTP protocol.
The basic commands of the smtp protocol include:

• HELO identifies the user to the server
• MAIL Initialize mail transfer mail from:
• RCPT identifies a single email recipient; often behind the MAIL command, there can be multiple rcpt to:
• DATA After single or multiple RCPT commands, it indicates that all email recipients have been identified and data transmission is initiated, ending with.
• VRFY is used to verify whether the specified user/mailbox exists; due to security reasons, servers often prohibit this command
• EXPN verifies whether the given mailbox list exists, expands the mailbox list, and is often disabled
• HELP Query what commands the server supports
• NOOP No operation, the server should respond OK
• QUIT End session
• RSET resets the session, the current transfer is canceled
• MAIL FROM Specified sender address
• RCPT TO specified recipient address

Generally, there are two methods for SMTP sessions. One is direct mail delivery, that is, if you want to send an email to zzz@163.com, then directly connect to the mail server of 163.com and send the letter to zzz@ 163.com; The other is to send an email after verification. The process is, for example, if you want to send an email to zzz@163.com, you do not send it directly to 163.com, but through another email on sina.com. Send via email. In this way, you need to first connect to the SMTP server of sina.com, then authenticate, and then submit the letter to 163.com to sina.com, and sina.com will help you deliver the letter to 163.com.

The command flow of the first method is basically as follows:
1. helo
2. mail from
3. rcpt to
4. data
5. quit
But the first sending method generally has limitations, that is, the email recipient specified by rcpt to must exist on this server, otherwise it will not be received. Let’s take a look at the code first:

#-*- encoding: gb2312 -*-
import os, sys, string
import smtplib

# 邮件服务器地址
mailserver = "smtp.163.com"
# smtp会话过程中的mail from地址
from_addr = "asfgysg@zxsdf.com"
# smtp会话过程中的rcpt to地址
to_addr = "zhaoweikid@163.com"
# 信件内容
msg = "test mail"

svr = smtplib.SMTP(mailserver)
# 设置为调试模式，就是在会话过程中会有输出信息
svr.set_debuglevel(1)
# helo命令，docmd方法包括了获取对方服务器返回信息
svr.docmd("HELO server")
# mail from, 发送邮件发送者
svr.docmd("MAIL FROM: <%s>" % from_addr)
# rcpt to, 邮件接收者
svr.docmd("RCPT TO: <%s>" % to_addr)
# data命令，开始发送数据
svr.docmd("DATA")
# 发送正文数据
svr.send(msg)
# 比如以 . 作为正文发送结束的标记,用send发送的，所以要用getreply获取返回信息
svr.send(" . ")
svr.getreply()
# 发送结束，退出
svr.quit()

#-*- encoding: gb2312 -*-
import os, sys, string
import smtplib
import base64

# 邮件服务器地址
mailserver = "smtp.163.com"
# 邮件用户名
username = "xxxxxx@163.com"
# 密码
password = "xxxxxxx"
# smtp会话过程中的mail from地址
from_addr = "xxxxxx@163.com"
# smtp会话过程中的rcpt to地址
to_addr = "yyyyyy@163.com"
# 信件内容
msg = "my test mail"

svr = smtplib.SMTP(mailserver)
# 设置为调试模式，就是在会话过程中会有输出信息
svr.set_debuglevel(1)
# ehlo命令，docmd方法包括了获取对方服务器返回信息
svr.docmd("EHLO server")
# auth login 命令
svr.docmd("AUTH LOGIN")
# 发送用户名，是base64编码过的，用send发送的，所以要用getreply获取返回信息
svr.send(base64.encodestring(username))
svr.getreply()
# 发送密码
svr.send(base64.encodestring(password))
svr.getreply()
# mail from, 发送邮件发送者
svr.docmd("MAIL FROM: <%s>" % from_addr)
# rcpt to, 邮件接收者
svr.docmd("RCPT TO: <%s>" % to_addr)
# data命令，开始发送数据
svr.docmd("DATA")
# 发送正文数据
svr.send(msg)
# 比如以 . 作为正文发送结束的标记
svr.send(" . ")
svr.getreply()
# 发送结束，退出
svr.quit()

#-*- encoding: gb2312 -*-
import os, sys, string, socket
import smtplib


class SMTP_SSL (smtplib.SMTP):
  def __init__(self, host='', port=465, local_hostname=None, key=None, cert=None):
    self.cert = cert
    self.key = key
    smtplib.SMTP.__init__(self, host, port, local_hostname)
    
  def connect(self, host='localhost', port=465):
    if not port and (host.find(':') == host.rfind(':')):
      i = host.rfind(':')
      if i >= 0:
        host, port = host[:i], host[i+1:]
        try: port = int(port)
        except ValueError:
          raise socket.error, "nonnumeric port"
    if not port: port = 654
    if self.debuglevel > 0: print>>stderr, 'connect:', (host, port)
    msg = "getaddrinfo returns an empty list"
    self.sock = None
    for res in socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM):
      af, socktype, proto, canonname, sa = res
      try:
        self.sock = socket.socket(af, socktype, proto)
        if self.debuglevel > 0: print>>stderr, 'connect:', (host, port)
        self.sock.connect(sa)
        # 新增加的创建ssl连接
        sslobj = socket.ssl(self.sock, self.key, self.cert)
      except socket.error, msg:
        if self.debuglevel > 0: 
          print>>stderr, 'connect fail:', (host, port)
        if self.sock:
          self.sock.close()
        self.sock = None
        continue
      break
    if not self.sock:
      raise socket.error, msg

    # 设置ssl
    self.sock = smtplib.SSLFakeSocket(self.sock, sslobj)
    self.file = smtplib.SSLFakeFile(sslobj);

    (code, msg) = self.getreply()
    if self.debuglevel > 0: print>>stderr, "connect:", msg
    return (code, msg)
    
if __name__ == '__main__':
  smtp = SMTP_SSL('192.168.2.10')
  smtp.set_debuglevel(1)
  smtp.sendmail("zzz@xxx.com", "zhaowei@zhaowei.com", "xxxxxxxxxxxxxxxxx")
  smtp.quit()

#-*- encoding: gb2312 -*-
import os, sys, string
import smtplib
import base64

# 邮件服务器地址
mailserver = "smtp.163.com"
# 邮件用户名
username = "xxxxxx@163.com"
# 密码
password = "xxxxxxx"
# smtp会话过程中的mail from地址
from_addr = "xxxxxx@163.com"
# smtp会话过程中的rcpt to地址
to_addr = "yyyyyy@163.com"
# 信件内容
msg = "my test mail"

svr = smtplib.SMTP(mailserver)
# 设置为调试模式，就是在会话过程中会有输出信息
svr.set_debuglevel(1)
# ehlo命令，docmd方法包括了获取对方服务器返回信息，如果支持安全邮件，返回值里会有starttls提示
svr.docmd("EHLO server")
svr.starttls() # <------ 这行就是新加的支持安全邮件的代码！
# auth login 命令
svr.docmd("AUTH LOGIN")
# 发送用户名，是base64编码过的，用send发送的，所以要用getreply获取返回信息
svr.send(base64.encodestring(username))
svr.getreply()
# 发送密码
svr.send(base64.encodestring(password))
svr.getreply()
# mail from, 发送邮件发送者
svr.docmd("MAIL FROM: <%s>" % from_addr)
# rcpt to, 邮件接收者
svr.docmd("RCPT TO: <%s>" % to_addr)
# data命令，开始发送数据
svr.docmd("DATA")
# 发送正文数据
svr.send(msg)
# 比如以 . 作为正文发送结束的标记
svr.send(" . ")
svr.getreply()
# 发送结束，退出
svr.quit()