10. Nodemailer

If you need to handle email bounces or complaints, integrate with email services that provide webhook support. Services like Mailgun and SendGrid offer webhook integrations for these purposes. Setting Up Webhooks with Mailgun:

For specific use cases, you might need to add custom headers to your emails. This can be useful for tracking or integrating with other systems. Adding Custom Headers:

For more secure authentication, especially with Gmail, you can use OAuth2. This avoids hardcoding credentials and enhances security. Setting Up OAuth2:

For more dynamic content within email templates, you can use template engines with placeholders. For instance, you can use Handlebars or Pug for advanced templating. Example with Handlebars and Nodemailer: Install Handlebars: Set Up Handlebars: Template File (views/welcome.hbs):

When sending a large number of emails, implement rate limiting or throttling to avoid being marked as spam or hitting rate limits of your email provider. Libraries like bottleneck can help with this. Example with Bottleneck:

If you need to send emails from multiple accounts, create multiple transporters and choose one based on the recipient or other criteria.

To test email functionality without sending real emails, use services like Mailtrap or Ethereal. These services provide a fake SMTP server to capture and view emails. Configure Mailtrap:

If you need to track email opens or clicks, integrate with an email tracking service or use webhooks. Services like Mailgun or SendGrid provide these features. Example with Mailgun:

For sending large attachments, consider using a file hosting service like AWS S3 and include a link to the file in your email instead of attaching the file directly. Example:

To handle high volumes of emails or to ensure reliable delivery, consider using an email queue. Libraries like Bull or Agenda can help with this. Example using Bull: Install Bull and Redis: Set up a Bull queue: