Retrying Failed User Reminder Notifications: Idempotency, DLQ Redrive, and Backoff
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dev.to
Short answer: retry failed user reminder notifications by combining queue nack and DLQ redrive with a durable idempotency record keyed by reminder ID, channel, and provider send, then apply exponential backoff so a rate-limited worker pool drains without sending the same reminder twice. The queue is allowed to deliver twice. The consumer is not allowed to notify twice. That distinction should drive the design, because at-least-once delivery makes duplicates normal rather than exceptional, while