verifalia
Verifalia email verification library for JavaScript: verify email addresses in real-time and check whether they are deliverable, invalid, or otherwise risky.
email-validator
Provides a fast, pretty robust e-mail validator. Only checks form, not function.
emailable
Email Verification that's astonishingly easy and low-cost. See https://emailable.com for details.
auth-validify
Your go-to JavaScript package for hassle-free form validation. Simplify error-checking, enhance user experience, and make your forms shine effortlessly.
