It verifies email addresses at the SMTP level without sending an email. One API call returns whether the mailbox exists, is disposable, has a full inbox, or is a catch-all domain.

Install with npm install sniffmail, call validateEmail("user@example.com"), get a verdict.

REST API available for non-Node stacks.

What it checks: SMTP mailbox existence (connects to the mail server, confirms the address is real),

disposable/temporary email detection (Mailinator, 10 Minute Mail, Guerrilla Mail, etc.), full inbox detection, catch-all domain identification, and MX record validation.

Most validators only check format and DNS. This goes to the mail server and asks.

500 free verifications on signup, no credit card.

Would love feedback, especially on edge cases or providers it misses.