Для Python версий 3.4 и выше.
Принятый ответ превосходен, но подходит только для более старых версий Python (2.x и 3.3). Я думаю, что нужно обновление.
Вот как вы можете сделать это в более новых версиях Python (3.4 и выше):
from email.message import EmailMessage
from email.utils import make_msgid
import mimetypes
msg = EmailMessage()
# generic email headers
msg['Subject'] = 'Hello there'
msg['From'] = 'ABCD <abcd@xyz.com>'
msg['To'] = 'PQRS <pqrs@xyz.com>'
# set the plain text body
msg.set_content('This is a plain text body.')
# now create a Content-ID for the image
image_cid = make_msgid(domain='xyz.com')
# if `domain` argument isn't provided, it will
# use your computer's name
# set an alternative html body
msg.add_alternative("""\
<html>
<body>
<p>This is an HTML body.<br>
It also has an image.
</p>
<img src="cid:{image_cid}">
</body>
</html>
""".format(image_cid=image_cid[1:-1]), subtype='html')
# image_cid looks like <long.random.number@xyz.com>
# to use it as the img src, we don't need `<` or `>`
# so we use [1:-1] to strip them off
# now open the image and attach it to the email
with open('path/to/image.jpg', 'rb') as img:
# know the Content-Type of the image
maintype, subtype = mimetypes.guess_type(img.name)[0].split('/')
# attach it
msg.get_payload()[1].add_related(img.read(),
maintype=maintype,
subtype=subtype,
cid=image_cid)
# the message is ready now
# you can write it to a file
# or send it using smtplib