Webhook endpoint returning 503 - need help wiring a DLQ for retry logic

The dashboard aggregator drops conversation:updated payloads when the lambda times out. Genesys Cloud retries the POST but we don’t get a clean ack. It’s throwing a 503 Service Unavailable every cycle. I’m routing the failed JSON into an SQS dead letter queue before the platform gives up. Here’s the handler stub:

if event['httpStatus'] >= 500:
 sqs.send_message(QueueUrl=DLQ_URL, MessageBody=json.dumps(event))
 return {'statusCode': 200}

The platform still marks it as delivery_failed. Not sure how to format the return object to break the retry loop.