Why Require Proof of Purchase Before a Survey?

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Asking for an invoice number improves data quality. Click to learn why this method filters for verified, useful survey responses.

When surveys are open to the public, you risk collecting biased or irrelevant responses. Requiring proof of purchase — such as an order ID or invoice number — ensures that feedback comes only from real customers.

This improves the quality of your data, reduces spam, and makes it easier to act on insights. It is especially useful for post-purchase or satisfaction surveys tied to product improvements.

In Gleam, you can use a custom action field to require proof before continuing to the rest of your campaign.