См. этот ответ, он работает для меня.
пример кода:
#send html email
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.header import Header
from email.utils import formataddr
msg = MIMEMultipart('alternative')
msg['From'] = formataddr((str(Header('MyWebsite', 'utf-8')), 'from@mywebsite.com'))
msg['To'] = 'to@email.com'
html = "email contents"
# Record the MIME types of text/html.
msg.attach(MIMEText(html, 'html'))
# Send the message via local SMTP server.
s = smtplib.SMTP('localhost')
# sendmail function takes 3 arguments: sender's address, recipient's address
# and message to send - here it is sent as one string.
s.sendmail('from@mywebsite.com', 'to@email.com', msg.as_string())
s.quit()