Amazon SNS DLQs are standard Amazon SQS queues. To receive notifications when undeliverable messages are moved to a DLQ, you can set up Amazon CloudWatch alarms. You can also analyze Amazon CloudWatch logs to troubleshoot message delivery failures more effectively.
Amazon SNS is a fully managed pub/sub messaging service. You can use Amazon SNS topics to decouple message publishers and subscribers, and simultaneously distribute messages to multiple endpoints, such as Amazon SQS queues, AWS Lambda functions, HTTP endpoints, email addresses, and mobile devices (SMS text messages and mobile push notifications).
To learn more about Amazon SNS dead-letter queues, see the following: