REC Change Proposal R0080 - Improvements to 'Failed to Deliver' CSS Messages was implemented on 27 June 2025. This Change enables a mechanism for the resending of CSS Messages that failed to deliver, to ensure successful retrieval of CSS Messages.

The following article and attached User Onboarding guide will provide the necessary background of the R0080 Change Proposal, and the relevant instructions to set up a new API connection with the CSS to retrieve any failed to deliver messages.

R0080 Background

Since the CSS go-live, some messages from CSS have failed to reach their intended recipients. This is often due to gateway outages or message rejections. Once a message fails, the CSS Provider cannot resend the message if the gateway is restored after the 12-hour re-try mechanism has concluded. Additionally, users have no visibility of where CSS messages have failed to deliver.

R0080 enables a mechanism of enabling users to retrieve these failed to deliver messages by:

• CSS creating a 'Held Message Register' which store all failed to deliver messages (holds messages that have still failed following the re-try process)
• Providing an API for parties to request resends of the held messages
• Notifying impacted parties, via the DCC Service Desk (ServiceNow) of failed messages

R0080 Solution Overview

Overview of the Message Resend Process:

• Messages that fail to deliver are stored within the CSS Held Messages Register
• Parties are notified of failed message instances (daily notification, auto-closure after 8 days)
• Parties use the Held Messages API to request the CSS resends the failed messages to their end point
• CSS re-sends the messages in chronological order (oldest first) to the parties registered webhook
• Messages are retained in the Held Messages Register for 12 months (from the date of entry), before removal

R0080 Onboarding Guide

The Code Manager has developed an Onboarding guide to help parties self-serve with their ability to adopt R0080's solution. Please find this attached at the bottom of this article.

The guide contains instructions on how to configure access to the new Resend Undelivered Messages API. This API is available to anyone who receives messages from the CSS.

Please note, while the use of the API is optional, there is no other mechanism to retrieve failed to deliver CSS Messages.

For support or any queries related to R0080 and its functionality, please contact the REC Code Manager.

For support or any queries related to the API, please contact the CSS Service Desk.