# Retrieve Undelivered Notifications
source: https://developer.mastercard.com/transaction-notifications/documentation/use-cases/retrieve-undelivered-notifications/index.md

If your webhook endpoint was unavailable when Mastercard sent a notification, use the `/notifications/undelivered-notifications` endpoint to retrieve any notifications that were not delivered. This ensures your records stay complete even if your service experiences downtime.

Mastercard retries failed notification deliveries at progressive intervals for up to 24 hours. After 24 hours, undelivered notifications are stored for up to seven days. Use this endpoint to:

* Recover notifications missed during planned or unplanned downtime.
* Verify that your webhook has received all expected notifications.
* Back-fill any gaps in your transaction records.

## How It Works {#how-it-works}

The following diagram shows the flow for retrieving undelivered notifications:
Diagram retrieveundeliverednotifications

1. Your service sends a `GET /notifications/undelivered-notifications` request to Mastercard, optionally including an `after` parameter to specify a starting sequence number.
2. Mastercard retrieves all stored notifications that failed to deliver to your webhook endpoint.
3. Mastercard returns the undelivered notifications along with a `nextCursor` value for pagination.
4. Your service processes the missed notifications and updates your records.
5. If more results exist, your service sends another request using the `nextCursor` value from the previous response.

Note: The API returns up to 100 notifications per request. Use the `after` parameter to paginate through larger result sets.

## Endpoint Structure {#endpoint-structure}


API Reference: `GET /notifications/undelivered-notifications`

## Next Steps {#next-steps}

* [View the full Open API specification](https://developer.mastercard.com/transaction-notifications/documentation/api-reference/index.md)
* [Review the API's error responses](https://developer.mastercard.com/transaction-notifications/documentation/codes-and-formats/index.md)