Python send HTML email with attachment

In this article, you will learn how to send HTML content in the mail with a file attachment using a secure SMTP server in Python programming language. In the previous article, we mentioned how to send simple mail to multiple recipients using an SMTP mail server. If you are unaware of this basic concept, please read the previous article.

Import SMTP library

To send mail using an SMTP mail server, first import the smtplib module. This module defines an SMTP client session object that helps in sending mail over the internet. The smtplib is a built-in module; we do not need to install it.

import smtplib

Import Email Package

The Python email package is combined with many classes and functions for sending simple to complex MIME text, MIME Base, and MIME multipart based mail. The encoder is imported to provide default encodings to MIME class constructors. It accepts only one argument, i.e., the message object to encode. The MIMEBase class always adds a Content-Type header and a MIME version header. The MIMEText is used to create MIME objects of the major type text. And the MIMEMultipart class is a subclass of the MIMEBase class. By using this class, we can call the attach() method for multipart messages.

import email
from email import encoders
from email.mime.base import MIMEBase
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

Create MIMEMultipart object

Here, we have created the following Multipart object and set the subject, from mail address, recipient mail address and the file name.

msg = MIMEMultipart("alternative")
msg["Subject"] = "multipart test"
msg["From"] = sender_email
msg["To"] = receiver_email
filename = "document.pdf"

HTML Message Part

Suppose we have the following HTML message part that we want to send in mail-

html = """\
<html>
  <body>
    <p><b>Python Mail Test</b><br>
       This is HTML email with attachment.<br>
       Click on <a href="https://www.etutorialspoint.com">Python Resources</a> 
       for more python articles.
    </p>
  </body>
</html>
"""

Before sending, first convert these into MIMEText object -

part = MIMEText(html, "html")

Next, add the above HTML/plain-text parts to MIMEMultipart message -

msg.attach(part)

Add Attachment

Next, open the PDF file and add the attachment. We have added the file as application/octet-stream and set the entire message object to payload using set_payload() method.

with open(filename, "rb") as attachment:
    part = MIMEBase("application", "octet-stream")
    part.set_payload(attachment.read())

Next, encoded the above parts to send in mail -

encoders.encode_base64(part)

Set headers

To send an attachment in mail, we need to add this in the header of the mail using add_header() method -

part.add_header(
    "Content-Disposition",
    "attachment", filename= filename
)
msg.attach(part)

Create SMTP Connection

Here, we have used smtplib.SMTP_SSL() to make SMTP communication over a secure encrypted SSL channel. The arguments for the SMTP_SSL() method are the SMTP server address and the port number. This requires authentication using client credentials (username and password)-

context = ssl.create_default_context()
with smtplib.SMTP_SSL("smtp.gmail.com", 465, context=context) as server:
    server.login(sender_email, password)
    server.sendmail(
        sender_email, receiver_email, msg.as_string()
    )

Complete Code: Python Send HTML Mail with Attachment

Here, we have merged the above-mentioned codes to send the HTML part with an attachment in an e-mail using a secure SSL SMTP connection.

import smtplib, ssl, email
from email import encoders
from email.mime.base import MIMEBase
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

sender_email = "SENDER_EMAIL_ADDRESS"
receiver_email = "RECEIVER_EMAIL_ADDRESS"
password = "PASSWORD"

#Create MIMEMultipart object
msg = MIMEMultipart("alternative")
msg["Subject"] = "multipart test"
msg["From"] = sender_email
msg["To"] = receiver_email
filename = "filename.pdf"

#HTML Message Part
html = """\
<html>
  <body>
    <p><b>Python Mail Test</b>
    <br>
       This is HTML email with attachment.<br>
       Click on <a href="https://www.etutorialspoint.com">Python Resources</a> 
       for more python articles.
    </p>
  </body>
</html>
"""

part = MIMEText(html, "html")
msg.attach(part)

# Add Attachment
with open(filename, "rb") as attachment:
    part = MIMEBase("application", "octet-stream")
    part.set_payload(attachment.read())
   
encoders.encode_base64(part)

# Set mail headers
part.add_header(
    "Content-Disposition",
    "attachment", filename= filename
)
msg.attach(part)

# Create secure SMTP connection and send email
context = ssl.create_default_context()
with smtplib.SMTP_SSL("smtp.gmail.com", 465, context=context) as server:
    server.login(sender_email, password)
    server.sendmail(
        sender_email, receiver_email, msg.as_string()
    )

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