SMTP发送邮件的时候，并没有特殊的通信语句告诉邮件服务器 谁是主送，谁是抄送/密送，这三个角色都是以同样的方式告诉邮件服务器的，然后重点在邮件内容里。
邮件内容分为头和体两部分（就像http），头部包含了各种meta信息，其中说明了谁要用to，谁要cc，谁要bcc.
一个典型的带to和bcc的邮件发送过程debug日志如下：
send: 'ehlo E42.lan
'
reply: b'250-smtp.qq.com
'
reply: b'250-PIPELINING
'
reply: b'250-SIZE 73400320
'
reply: b'250-AUTH LOGIN PLAIN
'
reply: b'250-AUTH=LOGIN
'
reply: b'250-MAILCOMPRESS
'
reply: b'250 8BITMIME
'
reply: retcode (250); Msg: b'smtp.qq.com
PIPELINING
SIZE 73400320
AUTH LOGIN PLAIN
AUTH=LOGIN
MAILCOMPRESS
8BITMIME'
send: 'AUTH PLAIN xxxxxxxxxxxxxxxxxxxxxxxxx
'
reply: b'235 Authentication successful
'
reply: retcode (235); Msg: b'Authentication successful'
send: 'mail FROM:<support@xxxxx.com> size=1412
'
reply: b'250 Ok
'
reply: retcode (250); Msg: b'Ok'
send: 'rcpt TO:<xxxxx@126.com>
'
reply: b'250 Ok
'
reply: retcode (250); Msg: b'Ok'
send: 'rcpt TO:<xxxxx@smail.nju.edu.cn>
'
reply: b'250 Ok
'
reply: retcode (250); Msg: b'Ok'
send: 'data
'
reply: b'354 End data with <CR><LF>.<CR><LF>
'
reply: retcode (354); Msg: b'End data with <CR><LF>.<CR><LF>'
data: (354, b'End data with <CR><LF>.<CR><LF>')
send: b'Content-Type: multipart/alternative; boundary="===============6519358828643049548=="
MIME-Version: 1.0
Accept-Language: zh-CN
Accept-Charset: ISO-8859-1,utf-8
From: support <support@xxxxx.com>
To: xxxxx@126.com
Subject: =?utf-8?b?5Yiw5pyf5o+Q6YaS?=
Bcc: xxxxx@smail.nju.edu.cn
--===============6519358828643049548==
Content-Type: text/html; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: base64
PCFET0N 这里省略一长串正文 tbD4K
--===============6519358828643049548==--
.
'
reply: b'250 Ok: queued as
'
reply: retcode (250); Msg: b'Ok: queued as'
data: (250, b'Ok: queued as')
send: 'quit
'
reply: b'221 Bye
'
reply: retcode (221); Msg: b'Bye'
下面是python代码：
#!/usr/bin/env python3
# coding: utf-8
#
# Created by dylanchu on 2019/7/5
import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.utils import formataddr
class MyMailer(object):
def __init__(self, config: dict):
""" config['bcc'] should be a list """
self.Host = config['host']
self.Port = config['port']
self.Email = config['email']
self.Password = config['password']
self.From = config['from']
self.using_ssl = config['using_ssl']
self.Bcc = config['bcc']
if not isinstance(self.Bcc, list):
raise Exception('passed in "bcc" should be a list')
def send_mail(self, recipient, subject, content):
if recipient == '' or subject == '' or content == '':
raise Exception('recipient/subject/content should not be empty!!')
# Create message container - the correct MIME type is multipart/alternative.
msg = MIMEMultipart('alternative')
msg["Accept-Language"] = "zh-CN"
msg["Accept-Charset"] = "ISO-8859-1,utf-8"
msg['From'] = formataddr([self.From, self.Email])
msg['To'] = recipient
msg['Subject'] = subject
# msg format should be 'plain' or 'html'
body = MIMEText(content, 'html', 'utf-8')
msg.attach(body)
if self.Bcc and '@' in self.Bcc[0]:
msg['Bcc'] = ','.join(self.Bcc)
recipient = [recipient] + self.Bcc
try:
if self.using_ssl:
smtp = smtplib.SMTP_SSL(self.Host, self.Port, timeout=30)
else:
smtp = smtplib.SMTP(self.Host, self.Port, timeout=30)
smtp.set_debuglevel(1)
smtp.login(self.Email, self.Password)
smtp.sendmail(self.Email, recipient, msg.as_string())
smtp.quit()
print("email sent successfully")
except Exception as e:
print("email sent failed with error: %s" % e)
作为to和bcc看到的邮件都是这样的：
