问如何使用python发送电子邮件给多个收件人？

EN

import email as em
import smtplib as smtp
import os

ENDPOINTS = {KEY: 'value@domain.com'}


class BoxWriter(object):

    def __init__(self):
        pass

    def dispatch(self, files, box_target, additional_targets=None, email_subject=None, body='New figures'):
        """
        Send an email to multiple recipients

        :param files: list of files to send--requires full path
        :param box_target: Relevant entry ENDPOINTS dict
        :param additional_targets: other addresses to send the same email
        :param email_subject: optional title for email
        """

        destination = ENDPOINTS.get(box_target, None)
        if destination is None:
            raise Exception('Target folder on Box does not exist')

        recipients = [destination]
        if additional_targets is not None:
            recipients.extend(additional_targets)

        subject = 'Updating files'
        if email_subject is not None:
            subject = email_subject

        message = em.MIMEMultipart.MIMEMultipart()
        message['From'] = 'user@domain.com'
        message['To'] = ', '.join(recipients)
        message['Date'] = em.Utils.formatdate(localtime=True)
        message['Subject'] = subject

        message.attach(em.MIMEText.MIMEText(body + '\n' +'Contents: \n{0}'.format('\n'.join(files))))

        for f in files:
            base = em.MIMEBase.MIMEBase('application', "octet-stream")
            base.set_payload(open(f, 'rb').read())
            em.Encoders.encode_base64(base)
            base.add_header('Content-Disposition', 'attachment; filename={0}'.format(os.path.basename(f)))
            message.attach(base)

        conn = smtp.SMTP('smtp.gmail.com', 587)
        un = 'user@gmail.com'
        pw = 'test1234'
        conn.starttls()
        conn.login(un, pw)
        conn.sendmail('user@domain.com', recipients, message.as_string())
        conn.close()

mail(["recipient1@email.com", "recipient2@email.com"],
   "Subject",
   "Message", 
   "attchachment")