您可以在将收件人电子邮件写入文本文件时尝试此操作

from email.mime.text import MIMEText
from email.header import Header
import smtplib

f =  open('emails.txt', 'r').readlines()
for n in f:
     emails = n.rstrip()
server = smtplib.SMTP('smtp.uk.xensource.com')
server.ehlo()
server.starttls()
body = "Test Email"
subject = "Test"
from = "me@example.com"
to = emails
msg = MIMEText(body,'plain','utf-8')
msg['Subject'] = Header(subject, 'utf-8')
msg['From'] =  Header(from, 'utf-8')
msg['To'] = Header(to, 'utf-8')
text = msg.as_string()
try:
   server.send(from, emails, text)
   print('Message Sent Succesfully')
except:
   print('There Was An Error While Sending The Message')

我提出了这个可导入模块函数。本例中使用的邮件服务器为gmail。它分为头和消息，所以你可以清楚地看到发生了什么:

import smtplib

def send_alert(subject=""):

    to = ['email@one.com', 'email2@another_email.com', 'a3rd@email.com']
    gmail_user = 'me@gmail.com'
    gmail_pwd = 'my_pass'
    smtpserver = smtplib.SMTP("smtp.gmail.com", 587)
    smtpserver.ehlo()
    smtpserver.starttls()
    smtpserver.ehlo
    smtpserver.login(gmail_user, gmail_pwd)
    header = 'To:' + ", ".join(to) + '\n' + 'From: ' + gmail_user + '\n' + 'Subject: ' + subject + '\n'
    msg = header + '\n' + subject + '\n\n'
    smtpserver.sendmail(gmail_user, to, msg)
    smtpserver.close()

实际上问题在于SMTP。发送邮件和电子邮件。MIMEText需要两个不同的东西。

电子邮件。MIMEText为电子邮件正文设置了“To:”标头。它仅用于向另一端的人显示结果，并且像所有电子邮件标题一样，必须是单个字符串。(请注意，它实际上不必与实际接收消息的人有任何关系。)

SMTP。另一方面，sendmail为SMTP协议设置消息的“信封”。它需要一个Python字符串列表，每个字符串都有一个地址。

所以，你需要做的就是将收到的两个回复结合起来。将msg['To']设置为单个字符串，但将原始列表传递给sendmail:

emails = ['a.com','b.com', 'c.com']
msg['To'] = ', '.join( emails ) 
....
s.sendmail( msg['From'], emails, msg.as_string())

要向多个收件人发送电子邮件，请将收件人添加为电子邮件id列表。

接收者= ['user1@email.com'， 'user2@email.com'， 'user3@email.com']

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

smtp_server = 'smtp-example.com'
port = 26 
sender = 'user@email.com'
debuglevel = 0

# add receivers as list of email id string
receivers = ['user1@email.com', 'user2@email.com', 'user3@email.com']

message = MIMEMultipart(
    "mixed", None, [MIMEImage(img_data, 'png'), MIMEText(html,'html')])
    message['Subject'] = "Token Data"
    message['From'] = sender
    message['To'] = ", ".join(receivers)
    try:

        server = smtplib.SMTP('smtp-example.com')
        server.set_debuglevel(1)
        server.sendmail(sender, receivers, message.as_string())
        server.quit()
        # print(response)

    except BaseException:
        print('Error: unable to send email')

下面的解决方案对我很有效。它成功地向多个收件人发送电子邮件，包括“抄送”和“密件抄送”。

toaddr = ['mailid_1','mailid_2']
cc = ['mailid_3','mailid_4']
bcc = ['mailid_5','mailid_6']
subject = 'Email from Python Code'
fromaddr = 'sender_mailid'
message = "\n  !! Hello... !!"

msg['From'] = fromaddr
msg['To'] = ', '.join(toaddr)
msg['Cc'] = ', '.join(cc)
msg['Bcc'] = ', '.join(bcc)
msg['Subject'] = subject

s.sendmail(fromaddr, (toaddr+cc+bcc) , message)

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())