/email-service-integration

name: email-service-integration
description: >
  Integrate email services with backends using SMTP, third-party providers,
  templates, and asynchronous sending. Use when implementing email
  functionality, sending transactional emails, and managing email workflows.

Email Service Integration

Table of Contents

• [Overview](#overview)
• [When to Use](#when-to-use)
• [Quick Start](#quick-start)
• [Reference Guides](#reference-guides)
• [Best Practices](#best-practices)

Overview

Build comprehensive email systems with SMTP integration, third-party email providers (SendGrid, Mailgun, AWS SES), HTML templates, email validation, retry mechanisms, and proper error handling.

When to Use

• Sending transactional emails
• Implementing welcome/confirmation emails
• Creating password reset flows
• Sending notification emails
• Building email templates
• Managing bulk email campaigns

Quick Start

Minimal working example:

# config.py
import os

class EmailConfig:
    MAIL_SERVER = os.getenv('MAIL_SERVER', 'smtp.gmail.com')
    MAIL_PORT = int(os.getenv('MAIL_PORT', 587))
    MAIL_USE_TLS = os.getenv('MAIL_USE_TLS', True)
    MAIL_USERNAME = os.getenv('MAIL_USERNAME')
    MAIL_PASSWORD = os.getenv('MAIL_PASSWORD')
    MAIL_DEFAULT_SENDER = os.getenv('MAIL_DEFAULT_SENDER', 'noreply@example.com')

# email_service.py
from flask_mail import Mail, Message
from flask import render_template_string
import logging
from datetime import datetime
import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

logger = logging.getLogger(__name__)
mail = Mail()

class EmailService:
    def __init__(self, app=None):
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the `references/` directory:

| Guide | Contents | |---|---| | [Python/Flask with SMTP](references/pythonflask-with-smtp.md) | Python/Flask with SMTP | | [Node.js with SendGrid](references/nodejs-with-sendgrid.md) | Node.js with SendGrid | | [Email Templates with Mjml](references/email-templates-with-mjml.md) | Email Templates with Mjml | | [FastAPI Email with Background Tasks](references/fastapi-email-with-background-tasks.md) | FastAPI Email with Background Tasks | | [Email Validation and Verification](references/email-validation-and-verification.md) | Email Validation and Verification |

Best Practices

✅ DO

• Use transactional email providers for reliability
• Implement email templates for consistency
• Add unsubscribe links (required by law)
• Use background tasks for email sending
• Implement proper error handling and retries
• Validate email addresses before sending
• Add rate limiting to prevent abuse
• Monitor email delivery and bounces
• Use SMTP authentication
• Test emails in development environment

❌ DON'T

• Send emails synchronously in request handlers
• Store passwords in code
• Send sensitive information in emails
• Use generic email addresses for sensitive operations
• Skip email validation
• Ignore bounce and complaint notifications
• Use HTML email with inline styles excessively
• Forget to handle failed email deliveries
• Send emails without proper templates
• Store email addresses without consent