Q: Email validation API or SMS OTP to filter junk signups — which catches more fake leads?

Q: Email validation API or SMS OTP to filter junk signups — which catches more fake leads?

A: They block different fakes, and the cost gap is real.

Email validation (an API that checks syntax, domain, mailbox existence, and whether it's a disposable/temp address) is cheap — fractions of a cent — and runs invisibly. It kills typo emails and throwaway addresses, but a determined fraudster spins up real-looking inboxes faster than you'd think.

SMS OTP (one-time passcode to a phone) is stronger proof of a real human, but it costs real money per message, adds friction that drops conversion, and gets defeated by virtual/VoIP numbers and SMS-receiving services.

Match the tool to the threat:
— Free or low-value lead-gen drowning in junk: email validation first, it's nearly free.
— Payouts tied to verified contactability (calls, appointments): SMS OTP, plus block VoIP number ranges.
— Layer them: validate email silently, trigger OTP only when the lead clears the cheap check and the payout justifies it.

Short version: email validation is cheap and catches throwaways; SMS OTP proves a human but costs money and friction. Cheap filter first, OTP only where it pays.

Still stuck? Drop your case in the comments.