SimpleVerifier Team · Reviewed
How do I verify email addresses on a signup form?
Call a verification API when the form is submitted, reject invalid addresses and known disposable domains, and let unconfirmed (risky) addresses through with a confirmation email. Use a short timeout that fails open, so a slow check never blocks a real signup. Do not verify on every keystroke.
A safe pattern
The steps, in order.
- On submit, call the verify endpoint once with a timeout of a few seconds.
- invalid: show a message asking for a different address (offer a typo suggestion).
- risky or a timeout: accept, then send a confirmation email so the owner proves the address.
- valid: continue.
SimpleVerifier's API
One GET or POST to /api/v1/verify returns status, reason and send advice. The Pro plan includes 10,000 API calls a month, and each key can make 120 calls a minute. Starter and Growth have no API access.
Related questions
- Should a risky address be rejected at signup?
- Usually not. Many real addresses are unconfirmable (catch-all, Yahoo, Microsoft consumer). Accept them and confirm by email.
Sources
Figures marked as ours come from SimpleVerifier’s own dated tests on made-up addresses, published with their data on the research page. No customer data is used, and we publish no accuracy percentage because we have no independent measurement to back one.
Do it now
Test it on a real address first
Type any address. It gets the same check the paid plans run: syntax, the domain’s mail servers and, where the provider allows it, a live mailbox check. Nothing is sent to the address.
Five checks a minute, no account needed. Nothing is sent to the address — we ask its mail server whether the mailbox exists, then disconnect.
Have a list? Sign in with Google and the first 100 addresses are checked free, with results to download. No card.
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