4 Best Javascript Email API Libraries

Nodemailer

Nodemailer is a module for Node.js applications to allow easy as cake email sending.

Mailslurp-client

MailSlurp is an email APl service that lets you create real email addresses in code.

Emailjs

Send emails, HTML, and attachments (files,streams, and strings)  from node.js to any SMTP server.

Postmark

Send emails with the greatest of ease! Postmark allows you to send your application emails

with high delivery rates, including bounce/spam processing and detailed statistics