EmailMessage 在发送的电子邮件中没有正确显示 python's email 和 smtplib 软件包

Question

我的邮件可以正确发送，但在收件人邮件中显示不正确。它看起来像这样:

: = ? utf - 8 b ? ? ?= & lt;……com>MIME-Version: 1.0内容类型:multipart/混合;边界=" ;=============== 5404281335870522242 = =,

--=============== 5404281335870522242 = =内容类型:文本/平原;charset ="utf-8"Content-Transfer-Encoding: base64

5 bck5pws55qe5a2u6laf5yw…

——===============5404281335870522242== Content-Type: image/png Content-Transfer-Encoding: base64 Content-Disposition: attachment;文件名="user.png"MIME-Version: 1.0

iVBORw0KGgo…

直接显示MIME字符串，除了Subject和From行(在To之后显示)以及纯文本中的所有正文。

这是我的代码:

import smtplib
import ssl
import mimetypes
from pathlib import Path
from email.message import EmailMessage
from email.utils import formataddr
import time
class EmailSender:
PORT = 465
CONTEXT = ssl.create_default_context()
def __init__(
self,
username,
password,
host,
):
self.username = username
self.password = password
self.host = host
self.mails = []
def _add_name_header(self, name="", mail_addr=""):
if name:
return formataddr((name, mail_addr))
else:
return mail_addr
def add_mail(
self,
from_email="",
from_name="",
to_email="",
to_name="",
subject="",
message_txt="",
files=None,
):
msg = EmailMessage()
msg["Subject"] = subject
msg["From"] = self._add_name_header(from_name, from_email)
msg["To"] = self._add_name_header(to_name, to_email)
msg.set_content(message_txt)
if not files is None:
for file_obj in files:
if file_obj.exists():
file = str(file_obj)
ctype, encoding = mimetypes.guess_type(file)
if ctype is None or encoding is not None:
# No guess could be made, or the file is encoded (compressed), so use a generic bag-of-bits type.
ctype = "application/octet-stream"
maintype, subtype = ctype.split("/", 1)
with file_obj.open("rb") as fp:
msg.add_attachment(
fp.read(),
maintype=maintype,
subtype=subtype,
filename=file_obj.name,
)
self.mails.append(msg)
def send(self, time_interval=1):
with smtplib.SMTP_SSL(
host=self.host, port=self.PORT, context=self.CONTEXT
) as server:
try:
server.login(user=self.username, password=self.password)
except Exception as e:
# Need process errors
raise e
for msg in self.mails:
server.send_message(msg)
time.sleep(time_interval)

我就这么做了:

sender = EmailSender(
username, password, host="smtp.163.com"
)
files = list(Path("D:/").glob("*.pdf"))
sender.add_mail(
from_email, from_name, to_email, to_name, subject, message_txt, files=None
)
sender.send(time_interval=10)

Answer 1

我是这个问题的OP。我刚刚自己解决了这个问题，我想和大家分享一下。

TLNR:在我的邮件中使用非ascii字符，所以使用msg = EmailMessage(EmailPolicy(utf8=True))代替msg = EmailMessage()。

我误解了SMTP.send_message文档中的这些句子:

如果from_addr和to_addr中有非ascii地址字符，并且服务器不通告SMTPUTF8支持抛出SMTPNotSupported错误。否则消息将被序列化使用其策略的克隆，将utf8属性设置为True，并且mail_options中增加SMTPUTF8和BODY=8BITMIME。

因为我添加了一个非ascii头到我的地址，我相信smtplib会自动为我使用utf8策略。但是在文件smtplib.py中，我看到了这个:

if from_addr is None:
# Some code
from_addr = email.utils.getaddresses([from_addr])[0][1]
if to_addrs is None:
# Some code
to_addrs = [a[1] for a in email.utils.getaddresses(addr_fields)]
# Some code
international = False
try:
"".join([from_addr, *to_addrs]).encode("ascii")
except UnicodeEncodeError:
# Some code
international = True

也就是说，函数只检查地址部分是否有非ascii字符，而不检查报头名称。

之后，消息被处理为纯ASCII内容，这可能没有问题，我不知道为什么，但不知何故，在To:xxx行之前和之后插入许多额外的/r字符，这使得SMTP服务器认为这可能是一个分隔符?并最终导致了这个问题。