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\r\n\'
reply: b\'250-smtp.qq.com\r\n\'
reply: b\'250-PIPELINING\r\n\'
reply: b\'250-SIZE 73400320\r\n\'
reply: b\'250-AUTH LOGIN PLAIN\r\n\'
reply: b\'250-AUTH=LOGIN\r\n\'
reply: b\'250-MAILCOMPRESS\r\n\'
reply: b\'250 8BITMIME\r\n\'
reply: retcode (250); Msg: b\'smtp.qq.com\nPIPELINING\nSIZE 73400320\nAUTH LOGIN PLAIN\nAUTH=LOGIN\nMAILCOMPRESS\n8BITMIME\'
send: \'AUTH PLAIN xxxxxxxxxxxxxxxxxxxxxxxxx\r\n\'
reply: b\'235 Authentication successful\r\n\'
reply: retcode (235); Msg: b\'Authentication successful\'
send: \'mail FROM:<support@xxxxx.com> size=1412\r\n\'
reply: b\'250 Ok\r\n\'
reply: retcode (250); Msg: b\'Ok\'
send: \'rcpt TO:<xxxxx@126.com>\r\n\'
reply: b\'250 Ok\r\n\'
reply: retcode (250); Msg: b\'Ok\'
send: \'rcpt TO:<xxxxx@smail.nju.edu.cn>\r\n\'
reply: b\'250 Ok\r\n\'
reply: retcode (250); Msg: b\'Ok\'
send: \'data\r\n\'
reply: b\'354 End data with <CR><LF>.<CR><LF>\r\n\'
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=="\r\nMIME-Version: 1.0\r\nAccept-Language: zh-CN\r\nAccept-Charset: ISO-8859-1,utf-8\r\nFrom: support <support@xxxxx.com>\r\nTo: xxxxx@126.com\r\nSubject: =?utf-8?b?5Yiw5pyf5o+Q6YaS?=\r\nBcc: xxxxx@smail.nju.edu.cn\r\n\r\n--===============6519358828643049548==\r\nContent-Type: text/html; charset="utf-8"\r\nMIME-Version: 1.0\r\nContent-Transfer-Encoding: base64\r\n\r\nPCFET0N 这里省略一长串正文 tbD4K\r\n\r\n--===============6519358828643049548==--\r\n.\r\n\'
reply: b\'250 Ok: queued as \r\n\'
reply: retcode (250); Msg: b\'Ok: queued as\'
data: (250, b\'Ok: queued as\')
send: \'quit\r\n\'
reply: b\'221 Bye\r\n\'
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：