When would you use delayed or scheduled messages, and what edge cases matter?

Use delayed and scheduled messages

Explains delayed delivery, scheduled work, reminders, retry timing, cancellation, and clock-related trade-offs.

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I would use delayed or scheduled messages when work needs to happen after a known delay, such as sending a reminder tomorrow or checking whether a payment is still pending in ten minutes. The message is hidden until its scheduled time, then a worker handles it like normal queued work. The handler still needs idempotency because the user or system state may have changed before the message becomes visible.

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Delayed delivery, reminders, retry scheduling, cancellation, clock behavior, idempotency, and user-facing expectations.

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Many products need future work: reminders, timeout checks, retries, cleanup, and delayed notifications. Scheduled messages are useful, but they are not the same thing as a full scheduler.
I would use delayed or scheduled messages when work needs to happen after a known delay, such as sending a reminder tomorrow or checking whether a payment is still pending in ten minutes. The message is hidden until its scheduled time, then a worker handles it like normal queued work. The handler still needs idempotency because the user or system state may have changed before the message becomes visible.
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I would design cancellation and state checks explicitly. If a user cancels an order before the scheduled reminder fires, the worker needs to check current state and skip the message. For many scheduled workflows, I would store the schedule in the database too, so the product can display it, cancel it, and recover from broker issues. Broker scheduling is convenient, but business state remains the source of truth.

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Assuming scheduled messages cannot become stale.
No way to cancel or skip work when state changes.
Using broker delay as the only source of business schedule truth.
Ignoring broker limits for long-term or high-volume schedules.

When would you use delayed or scheduled messages, and what edge cases matter?

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