ValueError：消息中最多可能有 1 个 To 标头

Question

我正在尝试编写一个非常基本的电子邮件发送脚本。这是我的代码..

import smtplib
from email.message import EmailMessage

msg = EmailMessage()
msg.set_content("Test message.")
msg['Subject'] = "Test Subject!!!"
msg['From'] = "myemail@gmail.com"

email_list = ["xyz@gmail.com", "abc@gmail.com"]

for email in email_list:
    msg['To'] = email
    server = smtplib.SMTP(host='smtp.gmail.com', port=587)
    server.starttls()
    server.login("myemail@gmail.com", "mypassword")
    server.send_message(msg)
    server.quit()

该脚本应该将邮件发送给多个收件人，因此，我需要msg['To']在循环迭代时更改该字段，但我在下面的回溯中收到以下错误。

Traceback (most recent call last):
  File "exp.py", line 66, in <module>
    msg['To'] = email
  File "/usr/lib/python3.8/email/message.py", line 407, in __setitem__
    raise ValueError("There may be at most {} {} headers "
ValueError: There may be at most 1 To headers in a message

我该如何解决？请帮忙。谢谢..

Answer 1

清理消息的“收件人”属性。

for email in email_list:
    msg['To'] = email
    server = smtplib.SMTP(host='smtp.gmail.com', port=587)
    server.starttls()
    server.login("myemail@gmail.com", "mypassword")
    server.send_message(msg)
    server.quit()
    del msg['To]

下面是抛出异常的代码：(\Python385\Lib\email\message.py)

def __setitem__(self, name, val):
    """Set the value of a header.

    Note: this does not overwrite an existing header with the same field
    name.  Use __delitem__() first to delete any existing headers.
    """
    max_count = self.policy.header_max_count(name)
    if max_count:
        lname = name.lower()
        found = 0
        for k, v in self._headers:
            if k.lower() == lname:
                found += 1
                if found >= max_count:
                    raise ValueError("There may be at most {} {} headers "
                                     "in a message".format(max_count, name))
    self._headers.append(self.policy.header_store_parse(name, val))