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How to send emails using API in Flask-Mail

Njoku Ifeanyi Gerald

What is Flask?

Flask is a Python micro web framework. Flask is “micro” because it omits native tools and libraries for an “only installs what you need” approach.

The Flask-Mail extension

In this shot, we’ll look at Flask-Mail. The Flask-Mail extension provides a simple interface to set up SMTPSimple Mail Transfer Protocol with your Flask application and to send messages from your views and scripts.

Configuring Flask-Mail

  • MAIL_SERVER: Name/IPInternet Protocol address of the email server.

  • MAIL_PORT: Port number of the particular server used.

  • MAIL_USERNAME: Username of the sender.

  • MAIL_PASSWORD: The password of the sender.

  • MAIL_USE_TLS: Enable/disable Transport Security Layer encryption.

  • MAIL_USE_SSL: Enable/disable Secure Sockets Layer encryption.

Install the dependencies

First, run the following commands to install the required dependencies:

pip install pipenv 
pipenv shell 
pipenv install Flask
pipenv install Flask-Mail

  • pip is a package manager for Python.
  • pipenv is a virtual environment in a Python file.


The class file

This file is created to help the user include any application configuration for the Flask app.

from flask import Flask, request, render_template
from flask_mail import Mail, Message
app = Flask(__name__)
# configuration of mail
app.config['MAIL_PORT'] = 587
app.config['MAIL_USERNAME'] = 'yourmail'

# use the app password created 
app.config['MAIL_PASSWORD'] = 'yourpassword'
app.config['MAIL_USE_TLS'] = True
app.config['MAIL_USE_SSL'] = False

# instantiating the mail service only after the 'app.config' to avoid error   
mail = Mail(app)

@app.route("/", methods=['GET', 'POST'])
def home():
    # try and except method
    #to avoid the app crashing if the message does not go through due to network or something
        # if it is a post request
        if request.method == 'POST':
            #getting the html inputs and referencing them
            sender = request.form['sender']
            recipient = request.form['recipient']
            message = request.form['message']
            subject = request.form['title']
            # inputing the message in the correct order
            msg = Message(subject,sender=sender,recipients =[recipient] )
            msg.body = message
            return "message Sent"
        return render_template('mail.html')
    except Exception as e:
        return f'<p>{e} </p>'
if __name__ == '__main__':
    # for app to run and debug to True = True)

The mail.html file

Create a folder and name it templates. Then, inside the templates folder, create a file and name it mail.html.

Inside mail.html, do this:

Visit to decrease the security of your mailbox. You have to create your web key as the password so it can allow less secure apps.

Here are some screenshots for how to get an app password from your Gmail.

Click on “Allow less secure apps”:

Go to the Gmail dashboard, click “Security” and then “App passwords”:

You will be prompted to input your password, so input it:

You will see a question asking if you want to generate an app password. Click on “Others” to generate an App password and click “Generate”:

Copy the generated app password, because that will be the password for the Flask-Mail app.




Njoku Ifeanyi Gerald

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