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Architecture

Author: Shaurya Sharma

This Email Service is a Flask application that provides the ability to:

  • Subscribe and unsubscribe users
  • Retrieve topics (with optional sub-options)
  • Send single or bulk emails
  • Upload and manage email templates
  • Manage and store daily reports, typically associated with topics

Key components:

  • Flask application (app.py) acts as the entry point, registering routes from routes.py.
  • MongoDB is used for storing subscribers, subscriptions, topics, templates, and daily reports data.
  • Brevo is utilized for sending emails via their Transactional Emails API.

Please read the following documents to get the complete picture of how to run, customize, and expand the Email Service.

Overview​

  1. App Initialization

    • The Flask application is created in app.py.
    • Cross-Origin Resource Sharing (CORS) is configured to allow requests from specified origins.

  2. Routing

    • Primary routes are defined in routes.py.
      • /subscribe (POST)
      • /unsubscribe (GET)
      • /topics (GET)
      • /send-email (POST)
      • /send-bulk-emails (POST)
      • /daily-reports/countries (GET)

  3. Database (MongoDB)

    • The database used is MongoDB, hosted with MongoDB Atlas on AWS.
    • Collections used:
      • countries, subscribers, subscriptions, topics, templates, reports, and email_reports.

  4. Templates & Rendering

    • Email templates are stored in the email_templates/ folder.
    • upload_templates.py loads or updates these templates into the templates collection.

  5. Business Logic

    • Subscribing/Unsubscribing is handled by subscribe_endpoint_v2.py and unsubscribe_endpoint.py.
    • Retrieving topics and daily reports involves get_topics_endpoint.py and daily_reports_countries_endpoint.py.
    • Sending emails is carried out by send_email_endpoint.py and send_bulk_emails_endpoint.py.

High-Level Flow​

  1. A request arrives at one of the routes.
  2. The endpoint handler (e.g., subscribe_endpoint_v2.py) processes input data, reads/writes to MongoDB.
  3. When sending an email, email_generator.py fetches the relevant template and merges it with data.
  4. Brevo (STMP Server as Service, Third Party) handles the actual email delivery.
  5. Logs and statuses are saved to the email_reports collection or used for debugging as needed.

Additional Notes​

  • For environment configuration, ensure your .env file includes: 
    MONGODB_URI=<your_connection_string>
    MONGODB_DB_EMAIL_SERVICE=email_service
    BREVO_API_KEY=<your_brevo_api_key>
    BREVO_SENDER_EMAIL=<sender_address>
    BREVO_SENDER_NAME=<sender_name>
  • Before deploying, set the environment variables accordingly and secure your secrets.
  • Run the server with python app.py to serve the Flask app at your configured port.