我在这里提供答案可能有点晚了，但是这个问题询问了一种发送HTML电子邮件的方法。使用像“email”这样的专用模块是可以的，但我们可以在不使用任何新模块的情况下实现相同的结果。这都归结为Gmail协议。

下面是我的简单示例代码，仅通过使用“smtplib”发送HTML邮件，而不使用其他任何代码。

```
import smtplib

FROM = "....@gmail.com"
TO = "another....@gmail.com"
SUBJECT= "Subject"
PWD = "thesecretkey"

TEXT="""
<h1>Hello</h1>
""" #Your Message (Even Supports HTML Directly)

message = f"Subject: {SUBJECT}\nFrom: {FROM}\nTo: {TO}\nContent-Type: text/html\n\n{TEXT}" #This is where the stuff happens

try:
    server=smtplib.SMTP("smtp.gmail.com",587)
    server.ehlo()
    server.starttls()
    server.login(FROM,PWD)
    server.sendmail(FROM,TO,message)
    server.close()
    print("Successfully sent the mail.")
except Exception as e:
    print("Failed to send the mail..", e)
```

下面是一个工作示例，使用smtplib以及CC和BCC选项从Python发送纯文本和HTML电子邮件。

https://varunver.wordpress.com/2017/01/26/python-smtplib-send-plaintext-and-html-emails/

#!/usr/bin/env python
import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

def send_mail(params, type_):
      email_subject = params['email_subject']
      email_from = "from_email@domain.com"
      email_to = params['email_to']
      email_cc = params.get('email_cc')
      email_bcc = params.get('email_bcc')
      email_body = params['email_body']

      msg = MIMEMultipart('alternative')
      msg['To'] = email_to
      msg['CC'] = email_cc
      msg['Subject'] = email_subject
      mt_html = MIMEText(email_body, type_)
      msg.attach(mt_html)

      server = smtplib.SMTP('YOUR_MAIL_SERVER.DOMAIN.COM')
      server.set_debuglevel(1)
      toaddrs = [email_to] + [email_cc] + [email_bcc]
      server.sendmail(email_from, toaddrs, msg.as_string())
      server.quit()

# Calling the mailer functions
params = {
    'email_to': 'to_email@domain.com',
    'email_cc': 'cc_email@domain.com',
    'email_bcc': 'bcc_email@domain.com',
    'email_subject': 'Test message from python library',
    'email_body': '<h1>Hello World</h1>'
}
for t in ['plain', 'html']:
    send_mail(params, t)

下面是示例代码。灵感来自Python Cookbook网站上的代码(找不到确切的链接)

def createhtmlmail (html, text, subject, fromEmail):
    """Create a mime-message that will render HTML in popular
    MUAs, text in better ones"""
    import MimeWriter
    import mimetools
    import cStringIO

    out = cStringIO.StringIO() # output buffer for our message 
    htmlin = cStringIO.StringIO(html)
    txtin = cStringIO.StringIO(text)

    writer = MimeWriter.MimeWriter(out)
    #
    # set up some basic headers... we put subject here
    # because smtplib.sendmail expects it to be in the
    # message body
    #
    writer.addheader("From", fromEmail)
    writer.addheader("Subject", subject)
    writer.addheader("MIME-Version", "1.0")
    #
    # start the multipart section of the message
    # multipart/alternative seems to work better
    # on some MUAs than multipart/mixed
    #
    writer.startmultipartbody("alternative")
    writer.flushheaders()
    #
    # the plain text section
    #
    subpart = writer.nextpart()
    subpart.addheader("Content-Transfer-Encoding", "quoted-printable")
    pout = subpart.startbody("text/plain", [("charset", 'us-ascii')])
    mimetools.encode(txtin, pout, 'quoted-printable')
    txtin.close()
    #
    # start the html subpart of the message
    #
    subpart = writer.nextpart()
    subpart.addheader("Content-Transfer-Encoding", "quoted-printable")
    #
    # returns us a file-ish object we can write to
    #
    pout = subpart.startbody("text/html", [("charset", 'us-ascii')])
    mimetools.encode(htmlin, pout, 'quoted-printable')
    htmlin.close()
    #
    # Now that we're done, close our writer and
    # return the message body
    #
    writer.lastpart()
    msg = out.getvalue()
    out.close()
    print msg
    return msg

if __name__=="__main__":
    import smtplib
    html = 'html version'
    text = 'TEST VERSION'
    subject = "BACKUP REPORT"
    message = createhtmlmail(html, text, subject, 'From Host <sender@host.com>')
    server = smtplib.SMTP("smtp_server_address","smtp_port")
    server.login('username', 'password')
    server.sendmail('sender@host.com', 'target@otherhost.com', message)
    server.quit()

从Office 365中的组织帐户发送电子邮件的最简单解决方案:

from O365 import Message

html_template =     """ 
            <html>
            <head>
                <title></title>
            </head>
            <body>
                    {}
            </body>
            </html>
        """

final_html_data = html_template.format(df.to_html(index=False))

o365_auth = ('sender_username@company_email.com','Password')
m = Message(auth=o365_auth)
m.setRecipients('receiver_username@company_email.com')
m.setSubject('Weekly report')
m.setBodyHTML(final_html_data)
m.sendMessage()

这里df是一个转换为html Table的数据帧，它被注入到html_template中

你可以试试我的邮件模块。

from mailer import Mailer
from mailer import Message

message = Message(From="me@example.com",
                  To="you@example.com")
message.Subject = "An HTML Email"
message.Html = """<p>Hi!<br>
   How are you?<br>
   Here is the <a href="http://www.python.org">link</a> you wanted.</p>"""

sender = Mailer('smtp.example.com')
sender.send(message)

对于python3，改进@taltman的回答:

使用email.message. emailmessage而不是email.message. message来构造email。 使用电子邮件。Set_content func, assign subtype='html'参数。而不是低级的func set_payload和手动添加头。 使用SMTP。send_message func而不是SMTP。Sendmail func发送电子邮件。 与块一起使用，可自动关闭连接。

from email.message import EmailMessage
from smtplib import SMTP

# construct email
email = EmailMessage()
email['Subject'] = 'foo'
email['From'] = 'sender@test.com'
email['To'] = 'recipient@test.com'
email.set_content('<font color="red">red color text</font>', subtype='html')

# Send the message via local SMTP server.
with smtplib.SMTP('localhost') as s:
    s.login('foo_user', 'bar_password')
    s.send_message(email)