One coupon per person: preventing coupon abuse.
A welcome discount for new customers, a code for newsletter subscribers: coupons are meant once per person, and some people redeem them again and again. This guide shows how coupon abuse works, what single-use codes and email checks miss and how to issue each coupon once per verified person.
- How coupon abuse works
- What single-use codes miss
- Coupons tied to a verified number
Christian Schätzlein, Founder and developer of Sendity
3 min read
Which redemptions are abuse?
Tap the suspicious redemptions, then reveal.
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First order New customer, as intended.
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Abuse Same delivery address as the first order, new alias.
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Abuse Throwaway address, same device again.
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Abuse A personal code that ended up on a deal site and was redeemed a hundred times.
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First order Looks fine.
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Cannot tell New address, new delivery address. Whether Carla ordered again, nothing tells.
Sign-ups by message. No form, no code.
Sendity is a sign-up widget for your website. Instead of filling in a form, your visitors send one short message via WhatsApp or email. Sendity checks who it came from and hands your site the name and the confirmed phone number or email address.
See how Sendity works →-
One message instead of a form Visitors tap send in WhatsApp or their email app. Nothing to type, no confirmation email to click.
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Confirmed by the message itself The contact comes from the sender of the message, so typos and made-up addresses never reach your list.
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Pay per confirmed contact Start with 1,000 free credits, no credit card. After that, prepaid packages with no subscription.
Most abuse is not fraud in the criminal sense. It is the same person taking a discount meant for someone new.
The usual patterns
A new customer discount with a new email alias each time, newsletter codes for every throwaway address, and personal codes passed on to deal sites.
Single-use codes
A code that works only once stops it from being shared widely. It does not stop the same person from requesting a new code with a new address.
Matching orders
Comparing delivery addresses, payment details and devices finds repeat customers after the fact. It catches some, blocks real households, and the discount is already gone.
Before the code is issued
The most effective check comes before the coupon: does this person already have one? A verified phone number answers that better than an email address.
Coupon after one message
With reverse OTP, the visitor sends one WhatsApp message and gets the code on your page. You issue one code per verified number and send nothing yourself.
One coupon per person in three steps.
Check first, then issue.
Visitor sends one message
Instead of typing an email address for the code.
You check the number
Has this verified number already received this coupon?
Code appears on your page
Personal and single-use, so sharing it does not help.
Code by email or by verified number?
What someone needs for a second discount.
| Aspect | Code by email | With Sendity |
|---|---|---|
| Second coupon | A new alias | Another number with a working WhatsApp account |
| Check happens | After the order, if at all | Before the code is issued |
| Households | Blocked when matching addresses | Each person has their own number |
| Your effort | Send emails, maintain lists | Store verified numbers |
What a verified number changes.
Discounts reach the people they were meant for.
Once per person
One coupon per verified number, not per alias.
Checked up front
No chasing repeat customers after the order.
One message
Faster than typing an address and waiting for the code email.
Live on your page in minutes.
Sendity runs as a compact widget on your page. Pick the path that fits your website.
Coupon abuse: common questions.
Can I store the number just for this?
Name the purpose in your privacy notice. If you only need to recognise repeats, store a salted hash instead of the number.
What about public codes in ads?
Codes meant for everyone cannot be limited per person. Use verification for personal discounts such as first orders and sign-up rewards.
Can someone use several numbers?
Yes, with a second SIM or virtual numbers. Each one takes effort, which makes a few euros of discount much less attractive.
Does it work in my shop system?
Sendity runs as a widget on any page. Your shop or a small backend issues the code once the signed result arrives.
Keep reading.
Reviewed for accuracy in by Christian Schätzlein.
Coupons once per person, verified by message.
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