如何通过 gmail-api for python 发送 HTML 格式的电子邮件

Question

使用来自GMail API Example: Send Mail 的示例代码，并在遵循身份验证规则后，通过 gmail 帐户发送以编程方式生成的电子邮件非常简单。示例中不明显的是如何将该电子邮件设置为 HTML 格式。

---

问题

如何使用 python 在我的 gmail-api 发送消息中获取 HTML 格式？

我有这个...

message_body = "Hello!\nYou've just received a test message!\n\nSincerely,\n-Test Message Generator\n"

我希望它是这样的......

Hello!
You've just received a test message!

Sincerely,
-Test Message Generator

---

来自 GMail-API 的示例源代码

以下是该示例的略微修改版本，但仍然有效：

import argparse
import base64
from pprint import pformat
from pprint import pprint
import httplib2
import os
from email.MIMEMultipart import MIMEMultipart
from email.MIMEText import MIMEText

from apiclient import discovery
from oauth2client import client
from oauth2client import tools
from oauth2client.file import Storage


SCOPES = 'https://mail.google.com/'
CLIENT_SECRET_FILE = 'client_secret.json'
APPLICATION_NAME = 'Test EMail App'


def get_credentials():
    """Gets valid user credentials from storage.

    If nothing has been stored, or if the stored credentials are invalid,
    the OAuth2 flow is completed to obtain the new credentials.

    Returns:
        Credentials, the obtained credential.
    """

    home_dir = os.path.expanduser('~')
    credential_dir = os.path.join(home_dir, '.credentials')
    if not os.path.exists(credential_dir):
        os.makedirs(credential_dir)
    credential_path = os.path.join(credential_dir,
                                   'gmail-python-quickstart.json')

    store = Storage(credential_path)
    credentials = store.get()
    if not credentials or credentials.invalid:
        flow = client.flow_from_clientsecrets(CLIENT_SECRET_FILE, SCOPES)
        flow.user_agent = APPLICATION_NAME
        if flags:
            credentials = tools.run_flow(flow, store, flags)
        else: # Needed only for compatibility with Python 2.6
            credentials = tools.run(flow, store)
        print('Storing credentials to ' + credential_path)
    return credentials

def create_message(sender, to, cc, subject, message_text):
    """Create a message for an email.

    Args:
    sender: Email address of the sender.
    to: Email address of the receiver.
    subject: The subject of the email message.
    message_text: The text of the email message.

    Returns:
    An object containing a base64url encoded email object.
    """
    print(sender + ', ' + to + ', ' + subject + ', ' + message_text)
    message = MIMEText(message_text)
    message['to'] = to
    message['from'] = sender
    message['subject'] = subject
    message['cc'] = cc
    pprint(message)
    return {'raw': base64.urlsafe_b64encode(message.as_string())}

def send_message(service, user_id, message_in):
    """Send an email message.

    Args:
    service: Authorized Gmail API service instance.
    user_id: User's email address. The special value "me"
    can be used to indicate the authenticated user.
    message: Message to be sent.

    Returns:
    Sent Message.
    """
    pprint(message_in)
    try:
        message = (service.users().messages().send(userId=user_id, body=message_in).execute())
        pprint(message)
        print ('Message Id: %s' % message['id'])
        return message
    except errors.HttpError, error:
        print ('An error occurred: %s' % error)

def main(cli):
    """Shows basic usage of the Gmail API.

    Creates a Gmail API service object and outputs a list of label names
    of the user's Gmail account.
    """


    credentials = get_credentials()
    http = credentials.authorize(httplib2.Http())
    service = discovery.build('gmail', 'v1', http=http)

    email_msg = create_message(cli.addr_from, cli.addr_to, cli.addr_cc, cli.subject, cli.message)
    msg_out = service.users().messages().send(userId = 'me', body = email_msg).execute()
    pprint(msg_out)


if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument('-m', '--message',   help = 'The message to send in the email', default='<MESSAGE = unfinished>')
    parser.add_argument('-t', '--addr_to',   help = 'the list of comma separated emails to send', default='cbsd.tools@gmail.com')
    parser.add_argument('-s', '--subject',   help = 'the email subject', default='<SUBJECT = undefined>')
    parser.add_argument('-c', '--addr_cc',   help = 'email CC\'s', default='')
    parser.add_argument('-f', '--addr_from', help = 'Email address to send from', default='cbsd.tools@gmail.com')
    cli = parser.parse_args()
    pprint(dir(cli))

    main(cli)

尽我所能，使用此代码及其变体，我无法获得 html 格式的代码，也无法获得简单的转义字符来在需要的位置创建回车。

---

这是没有用的

尝试以下方法也无效：

1. 修改line 69 以添加额外的消息字典参数...即。
   • {'raw': base64.urlsafe_b64encode(message.as_string()), 'payload': {'mimeType': 'text/html'}}
   • 如GMail API Docs 中所述
2. 在消息文本中添加各种转义的反斜杠：
   • \n... 即：\\n 或 \\\n，只是呈现为那些确切的字符
   • 添加 <br> </br> <br/> 并没有添加新行，而是呈现为那些确切的字符
   • 添加 \r 并没有添加新行，只是呈现为那个确切的字符

---

这不是重复问题的原因

• This SO link deals with multipart/signed messages
  • 我对多部分消息传递不感兴趣，因为它是一个不雅的解决方案。我希望整个消息是HTML。
  • 此外，此链接没有接受的答案，并且存在的一个答案是非答案，因为它只是表明他们正在向 Google 发送问题陈述。
• 这个处理的是c#，因为我是用python写的，所以我对它不感兴趣
  • This one also uses SMTP which I'm not interested in
• This one is for Rails

Answer 1

在进行了大量研究之后，我开始研究消息处理的 python 端，并注意到一个 python 对象实际上正在将要发送的消息构造为 base64 编码到 gmail-api 消息对象构造函数中。

从上面查看第 63 行：message = MIMEText(message_text)

最终对我有用的一个技巧，在尝试修改标头值和有效负载字典（它是 message 对象的成员）之后，设置 (@987654324 @):

• message = MIMEText(message_text, 'html') 'html'作为MIMEText对象构造函数的第二个参数

---

Google 为他们的 gmail API 提供的默认代码只告诉你如何发送纯文本电子邮件，但他们隐藏了他们是如何做到的。 翼... message = MIMEText(message_text)

我必须查找 python 类 email.mime.text.MIMEText 对象。 在那里您将看到 MIMEText 对象的构造函数的定义：

• 类 email.mime.text.MIMEText(_text[, _subtype[, _charset]]) 我们想明确地将一个值传递给_subtype。在这种情况下，我们希望通过：'html' 作为_subtype。

---

现在，Google 或 Python mime.text.MIMEText 对象将不再有意外的自动换行应用于您的消息

---

固定密码

def create_message(sender, to, cc, subject, message_text):
    """Create a message for an email.

    Args:
    sender: Email address of the sender.
    to: Email address of the receiver.
    subject: The subject of the email message.
    message_text: The text of the email message.

    Returns:
    An object containing a base64url encoded email object.
    """
    print(sender + ', ' + to + ', ' + subject + ', ' + message_text)
    message = MIMEText(message_text,'html')
    message['to'] = to
    message['from'] = sender
    message['subject'] = subject
    message['cc'] = cc
    pprint(message)
    return {'raw': base64.urlsafe_b64encode(message.as_string())}

Answer 2

试试这个：

    def CreateMessage(emailSubject, emailTo, emailFrom, message_body, emailCc, html_content=None):
        try:
            message = MIMEMultipart('alternative')
            message['to'] = emailTo
            message['from'] = emailFrom
            message['subject'] = emailSubject
            message['Cc'] = emailCc
            body_mime = MIMEText(message_body, 'plain')
            message.attach(body_mime)
            if html_content:
                html_mime = MIMEText(html_content, 'html')
                message.attach(html_mime)
            return {
                'raw': base64.urlsafe_b64encode(
                    bytes(
                        message.as_string(),
                        "utf-8")).decode("utf-8")}
        except Exception as e:
            print('Error in CreateMessage()', e)
            return '400'