Guides

One page per place a form meets a real person. Each ends with what the verification does not do.

• Email validation API for signup formsValidate the address on submit, reject only what is certainly wrong, and never lose a real user to a maybe.
• Verify an email address on form submitThe mechanics: where the call lives, what to show for each reason, and how to keep the form from waiting on a slow mail server.
• Block disposable email addresses at signupflags.disposable on every response, from a list rebuilt daily, plus role-account and free-provider flags for your own policy.
• Email verification: unknown and catch-all, what to doWhy a verifier that does not guess answers unknown, why catch-all is risky and not valid, and what your code should do with each.
• Email validation for checkout and lead formsAt checkout, never block a paying customer; on a lead form, use the flags for quality. One API, two policies.