Every free tier gets farmed
Someone burns forty throwaway addresses to reset a trial and your metrics stop meaning anything. Signup counts inflate, activation rate collapses, onboarding emails bounce, and your ESP starts throttling you because a share of your sends go nowhere.
Then there is the honest failure: gmial.com, yaho.com. That user meant to sign up. They will never receive the confirmation email, and they will never come back to find out why.
How it works
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1
Verify on blur or on submit, server-side.
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2
Block disposable and invalid. Nothing else.
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3
Suggest a correction for likely typos rather than throwing a generic error.
Get the UX right or you will cost yourself more signups than you save
Never block catch-all or role-based addresses at signup. Plenty of legitimate companies run catch-all domains, and ops@ is a real buyer. Blocking these is how you silently reject enterprise accounts.
Fail open on timeout. A verification outage must never become a signup outage.
Write a specific error. “That address can't receive mail — check for a typo?” converts. “Invalid email” makes people leave.
Verify server-side only. Client-side checks are advisory, and the key leaks.
What it changes
| Before | After |
|---|---|
| Signup count inflated by throwaways | A signup number you can plan against |
| Activation rate diluted by fake accounts | Activation rate reflecting real users |
| Onboarding emails bouncing | Sender reputation intact |
| Typo signups silently lost | Typo caught while the user is still on the page |
Will this slow down my signup form?
Average response is under 500ms and it runs in parallel with your other validation. Set a two to three second timeout and fail open.
Should I block free providers like Gmail?
Only if your product is genuinely enterprise-only, and know that you will reject real founders and consultants. Usually not worth it.
Does this replace email confirmation?
No. Verification stops bad addresses at the door; confirmation proves ownership. Do both — verification is what makes the confirmation arrive.
How much does it cost per signup?
$0.00075. A thousand signups costs 75 cents.
What about existing users?
Bulk verify your users table once by CSV to find the addresses that have decayed since signup.
Add real-time verification to your signup form — 100 free credits, no card required.