Send mail with attachments in Python Program

What will I Learn?

This tutorial teaches you how to send email with attachments in Python Programming.

Difficulty and Requirements

Same as previous tutorials

Tutorial Content

SMTP:

SMTP stands for SImple Mail Transfer Protocol is a electronic mail transmitter which uses Transmission Control Protocol port no. 25 to exchange data between mail servers.
Python has a great module called smtplib which defines an SMTP client session object which is used to send mail to any device that is connected to internet using SMPT
or ESMPT listener daemon, which defines the way of communications between sender and receiver .

Starting the coding part, at first we will import the smtplib module

import smtplib

Now we will define sender and receiver email in string format.

sender = "[email protected]"
receiver = "[email protected]"

To format email properly we will define a message with proper headers From, To and Subject which will be separated from the body of the email using blank line.

msg = """From: From Person <[email protected]>
To: To Person <[email protected]>
Subject: Sending Email using Python

I learned to send email using Python programming on programminghub tutorial.
"""

Now we define SMTP object named server which will be used to send emails. smtplib.SMTP method is called to connect to the SMTP server which
furthers calls SMTP connect()
method when host and port parameters are passed. We are using gmail to send email so we will pass gmail host and it's port number.

server = smtplib.SMTP('smtp.gmail.com',587)

Now, starttls() method is called to encrypt the following SMTP commands. As we will be passing valuable information like password , message in coming lines of code we need to call
this method. TLS stands for Transport Layer Security.

server.starttls()

We need to login to gmail server to send email. So we will call login() method for this. This method will take two arguements : sender address and it's password which will be
used to authenticate and login
into sender's SMTP server.

server.login(sender, "Sender_gmail_password")

Now we are logged in , we will send email by calling sendmail() method. This method takes three arguments : sender's email, receiver's email and message that needs to be sent.
It will construct required envelope form sender's email and receiver's email and transfers message without modifying headers.
After email is sent we need to quit the SMTP connection and end it's session so we will call quit()

server.quit()

Our final code:

import smtplib
sender = "[email protected]"
receiver = "[email protected]"
msg = """From: From Programminghub <[email protected]>
To: To Learner <[email protected]>
Subject: Sending Email using Python
I learned to send email using Python programming on programminghub tutorial.
"""
server = smtplib.SMTP('smtp.gmail.com',587)
server.starttls()
server.login(sender, "Sender_gmail_password")
server.sendmail(sender, receiver, msg)
server.quit()

Output:

Send attachment in email

For this we will add one more import of base64 module

import base64

base64 is a python module which provides functions to encode binary data to printable ASCII characters and decode it back. Now will open the file to read and we will encode that file into
base64 format.

file= "/path/filename.extension"
read_file = open(file, "rb")
file_content = readfile.read()
encodedcontent = base64.b64encode(file_content)

open() opens the file which take two arguments: path to file and mode. We opened /path/filename.extension in binary file read mode here. read() allows reading binary
data from opened files. To know more about working with files in python please visit here.
b64encode() method of base64 module is used to encode data which was assigned to file.
As we will be sending our email in different parts we need to set content-type to multipart/mixed. Then within boundries which is specified by two hyphens(- -) we will define text and attachment
part.We will define marker as AUNIQUEMARKER.
one defines the header, two defines the action to be taken and three defines the attachment section.
Thus three parts are defined as:

one = """From: From Programminghub <[email protected]>
To: To Learner <[email protected]>
Subject: Sending Email using Python
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=%s
--%s
""" % (marker, marker)

We can see that in one, header is well defined and MIMEVERSION is set to 1.0.
MIME stands for Multi-Purpose Internet Mail Extensions that
allows us to exchange different kinds of data filessuch as audio, video, images,etc.

two = """Content-Type: text/plain
Content-Transfer-Encoding:8bit

%s
--%s
""" % (body,marker)


three = """Content-Type: multipart/mixed; name=\"%s\"
Content-Transfer-Encoding:base64
Content-Disposition: attachment; file=%s

%s
--%s--
""" %(file, file, encoded_content, marker)

(file, file, encoded_content, marker) replaces the values in three also same things happens in other parts where values can be replaced.

We will define msg which holds the message to be send by combining all above three parts and send it.

msg=one + two + three

Combining with our previous final code and these new code lines our new final code looks like:

import smtplib
import base64
sender = '[email protected]'
receiver = '[email protected]'
file = "/path/filename.extension"
file_read = open(file, "rb")
file_content = file_read.read()
encoded_content = base64.b64encode(file_content) 
marker = "AUNIQUEMARKER"
body = """
I learned to send email using Python programming on programminghub tutorial.
"""
one = """From: From Programminghub <[email protected]>
To: To Learner <[email protected]>
Subject: Sending Email using Python
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=%s
--%s
""" % (marker, marker)
two = """Content-Type: text/plain
Content-Transfer-Encoding:8bit
%s
--%s
""" % (body, marker)
three = """Content-Type: multipart/mixed; name=\"%s\"
Content-Transfer-Encoding:base64
Content-Disposition: attachment; file=%s
%s
--%s--
""" % (file, file, encoded_content, marker)
msg = one + two + three
server = smtplib.SMTP('smtp.gmail.com', 587)
server.starttls()
server.login(sender, "Sender_Password_Here")
server.sendmail(sender, receiver, msg)
server.quit()