Dead letter queues on AWS Lambda can give developers more control over message handling for all asynchronous invocations, including those delivered via AWS events (S3, SNS, IoT, etc). Periodic review of Lambda Dead letter Queues can help ensure the availability of applications and functions.
In AWS Console -
In Terraform -
References:
https://docs.aws.amazon.com/lambda/latest/dg/invocation-async.html#invocation-dlq
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/lambda_function#dead_letter_config