# Customer Email Check

Source: https://docs.gocardless.com/docs/optimise/prefill-customer-details/customer-email-check

# Customer Email Check

When a billing request has customer details captured — via a linked customer record, prefilled data, or a payer who has already started the flow — GoCardless shows an email verification prompt when the authorisation link is opened.

This prevents a common issue where merchants mix reusable payment links with individual authorisation links, causing customers to inadvertently complete someone else's billing request.

## How it works

When the authorisation link is opened:

1. The payer is prompted to enter their email address.
2. **If the email matches** the captured email — the payer proceeds with the current billing request flow.
3. **If the email does not match** — GoCardless attempts to generate a new authorisation link (possible when the billing request was created from a pay link or plan link) and redirects the payer to a new, empty flow.
4. **If a new link cannot be generated** — an error page is shown.

If no customer details are captured on the billing request, the email check is skipped and the flow proceeds as normal.

## Happy path: email matches

The payer enters the email matching the captured one and proceeds with the existing flow.

![Customer Email Check: Submit the email matching the captured one](/images/docs/optimise/prefill-customer-details/customer-email-check/screenshot_2023-11-27_at_08.30.47.png)

![Customer Email Check: Resume flow when email matches](/images/docs/optimise/prefill-customer-details/customer-email-check/screenshot_2023-11-27_at_08.31.46.png)

## Happy path: new flow generated

The payer enters an email that does not match. GoCardless generates a new authorisation link and redirects the payer to a fresh, empty flow.

This is possible when the billing request was created from a pay link or a plan link.

![Customer Email Check: Submit the email which does not match the captured one](/images/docs/optimise/prefill-customer-details/customer-email-check/screenshot_2023-11-27_at_08.38.31.png)

![Customer Email Check: Create a new flow when emails don't match](/images/docs/optimise/prefill-customer-details/customer-email-check/screenshot_2023-11-27_at_08.42.23.png)

## Unhappy path: new flow cannot be generated

The payer enters a non-matching email but the billing request was not created from a pay link or plan link — so a new link cannot be generated automatically. An error page is displayed.

![Customer Email Check: Submit the email which does not match the captured one](/images/docs/optimise/prefill-customer-details/customer-email-check/screenshot_2023-11-27_at_08.38.31.png)

![Customer Email Check: Error when emails don't match and new link cannot be generated](/images/docs/optimise/prefill-customer-details/customer-email-check/screenshot_2023-11-27_at_08.39.30.png)

## What's next?

  
#### [Prefill customer details](/docs/optimise/prefill-customer-details)

Learn how to prefill customer details on billing requests to trigger the email check.

  
#### [Billing Requests](/docs/collect-payments/setting-up-mandates)

Set up mandates using Billing Requests.