Send an E-mail with Python Flask

Web-based applications typically require the ability to send mail to the user/client. Flask doesn't have an out of the box solution to send mail.

Instead, the Flask-Mail extension makes it easy to establish a simple interface with any email server.

Email generally uses two protocols, one for sending mails (smtp) and one for receiving mail (pop3). This article is about sending mails.

Introduction

First, the Flask-Mail extension should be installed with the help of the pip utility.

pip install Flask-Mail

You then need to configure the Flask-Mail by setting the values for the following application parameters.

• MAIL_SERVER
• MAIL_USE_TLS
• MAIL_USE_SSL
• MAIL_DEBUG
• MAIL_USERNAME
• MAIL_PASSWORD
• MAIL_DEFAULT_SENDER
• MAIL_MAX_EMAILS
• MAIL_SUPPRESS_SEND
• MAIL_ASCII_ATTACHMENTS

The flask-mail module contains definitions of the following important classes.

The Mail class manages email messaging requirements.The class constructor takes the form of:

flask-mail.Mail(app = None)

Mail class methods include: send(), connect() and send_message().

The Message class encapsulated an email.The Message class constructor has several parameters:

flask-mail.Message(subject, recipients, body, html, sender, cc, bcc,
   reply-to, date, charset, extra_headers, mail_options, rcpt_options)

Message class method attach () - Add attachment for mail.This method takes the following parameters:

• filename : The name of the file
• content_type : MIME type
• data - file data

You can use add_recipient() to add another recipient to the message.

Mail config and functions

In the example below, the SMTP server for the Google gmail service is used as the MAIL_SERVER for the Flask-Mail configuration.

Step 1: Import the Mail and Message classes from the flask-mail module in the code.

from flask_mail import Mail, Message

Step 2: Configure server parameters

app.config['MAIL_SERVER']='smtp.gmail.com'
app.config['MAIL_PORT'] = 465
app.config['MAIL_USERNAME'] = '[email protected]'
app.config['MAIL_PASSWORD'] = '*****'
app.config['MAIL_USE_TLS'] = False
app.config['MAIL_USE_SSL'] = True

Step 3: Create an instance of the Mail class.

mail = Mail(app)

Step 4: The Message object is set in a Python function that is mapped by the URL rule ('/').

@app.route("/")
def index():
   msg = Message('Hello', sender = '[email protected]', recipients = ['[email protected]'])
   msg.body = "This is the email body"
   mail.send(msg)
   return "Sent"

Flask mail example

The entire code is as follows.Run the following script in the Python shell and access localhost:5000/.

from flask import Flask
from flask_mail import Mail, Message

app = Flask(__name__)
mail= Mail(app)

app.config['MAIL_SERVER']='smtp.gmail.com'
app.config['MAIL_PORT'] = 465
app.config['MAIL_USERNAME'] = '[email protected]'
app.config['MAIL_PASSWORD'] = '*****'
app.config['MAIL_USE_TLS'] = False
app.config['MAIL_USE_SSL'] = True
mail = Mail(app)

@app.route("/")
def index():
   msg = Message('Hello', sender = '[email protected]', recipients = ['[email protected]'])
   msg.body = "Hello Flask message sent from Flask-Mail"
   mail.send(msg)
   return "Sent"

if __name__ == '__main__':
   app.run(debug = True)

Note that security in the Gmail service can prevent this login attempt. If you use gmail smtp server, you might have to reduce the security level.