我使用python 3.6和以下代码为我工作

email_send = 'xxxxx@xxx.xxx,xxxx@xxx.xxx'
server.sendmail(email_user,email_send.split(','),text)    

这真的很管用，我花了很多时间尝试多种变体。

import smtplib
from email.mime.text import MIMEText

s = smtplib.SMTP('smtp.uk.xensource.com')
s.set_debuglevel(1)
msg = MIMEText("""body""")
sender = 'me@example.com'
recipients = ['john.doe@example.com', 'john.smith@example.co.uk']
msg['Subject'] = "subject line"
msg['From'] = sender
msg['To'] = ", ".join(recipients)
s.sendmail(sender, recipients, msg.as_string())

我尝试了下面的方法，效果很好:)

rec_list =  ['first@example.com', 'second@example.com']
rec =  ', '.join(rec_list)

msg['To'] = rec

send_out = smtplib.SMTP('localhost')
send_out.sendmail(me, rec_list, msg.as_string())

尝试声明一个包含所有收件人和cc_收件人的列表变量为字符串，而不是循环遍历它们，如下所示:

from email.MIMEMultipart import MIMEMultipart
from email.MIMEText import MIMEText
import smtplib

recipients = ["malcom@example.com","reynolds@example.com", "firefly@example.com"]
cc_recipients=["serenity@example.com", "inara@example.com"]
msg = MIMEMultipart()
msg["Subject"] = "Example"
msg["From"] = "me@example.com"
msg["To"] = ', '.join(recipients)
msg["Cc"] = ', '.join(cc_recipients)
body = MIMEText("example email body")
msg.attach(body)
smtp = smtplib.SMTP("mailhost.example.com", 25)
for recipient in recipients:
    smtp.sendmail(msg["From"], recipient, msg.as_string())
for cc_recipient in cc_recipients:
    smtp.sendmail(msg["From"], cc_recipient, msg.as_string())
smtp.quit()

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

def sender(recipients): 

    body = 'Your email content here'
    msg = MIMEMultipart()

    msg['Subject'] = 'Email Subject'
    msg['From'] = 'your.email@gmail.com'
    msg['To'] = (', ').join(recipients.split(','))

    msg.attach(MIMEText(body,'plain'))

    server = smtplib.SMTP('smtp.gmail.com', 587)
    server.starttls()
    server.login('your.email@gmail.com', 'yourpassword')
    server.send_message(msg)
    server.quit()

if __name__ == '__main__':
    sender('email_1@domain.com,email_2@domain.com')

它只适用于我send_message函数和使用列表中的连接函数与收件人，python 3.6。

几个月前我发现了这一点，并在博客上发表了相关文章。总结如下:

如果您想使用smtplib向多个收件人发送电子邮件，请使用email. message。add_header('To'， eachRecipientAsString)来添加它们，然后当您调用sendmail方法时，使用email.Message.get_all('To')将消息发送给所有它们。抄送和密送收件人也是如此。