All the content are treated as a simple text at when you send a text message using Python. Even if you include HTML tags in a text message, it will display as simple text and HTML tags will not be formatted according to HTML syntax. But Python provides option to send an HTML message as actual HTML message. For example you can see below code-

#!/shiva/bin/python

import smtplib

message = """From: From Person 
To: To Person 
MIME-Version: 1.0
Content-type: text/html
Subject: SMTP HTML e-mail test

This is an e-mail message to be sent in HTML format

This is HTML message.
This is headline.
"""

try:
   smtpObj = smtplib.SMTP('localhost')
   smtpObj.sendmail(sender, receivers, message)         
   print "Successfully sent email"
except SMTPException:
   print "Error: unable to send email"