How to Send Emails in Express.js: SMTP and Email API Methods Explained

Express.js applications can send email through SMTP-based libraries such as Nodemailer and emailjs or through an email API such as Mailtrap’s Node.js client. The tutorial demonstrates setting up Express endpoints that accept recipient, subject, and message data, validate required fields, use JSON parsing and CORS middleware, protect credentials in environment variables, and return appropriate success or error responses. Nodemailer uses an SMTP transporter with async/await, while emailjs uses an SMTP client and callbacks; the email-templates package with Pug supports personalized HTML, text, and subject templates for multiple recipients. Mailtrap’s API-based approach supports plain-text and HTML messages, multiple recipients, attachments uploaded with Multer, embedded inline images, asynchronous personalized sends, and bulk email streams. Throughout, the examples emphasize configuring verified sender details and SMTP or API credentials securely, restricting permissive CORS settings in production, and using error handling to improve reliability.

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