How to Prevent Duplicate SMS Password-Reset Alerts Under Timeout and Retry Conditions

Duplicate SMS password-reset notifications can occur when developers treat a timed-out request as a failed send and immediately retry, rather than as an unknown outcome. A robust approach requires persisting an idempotency key and expiry before dispatch, then delegating retries to a background worker that can reconcile the original attempt's status. Status polling and retry logic must be kept strictly separate, as combining them in a single function is a common source of duplicate messages. Every dispatch attempt should also check the current time against the token's expiry, halting sends once delivery would no longer be meaningful. The guiding contract is to admit each password-reset notification exactly once, retain evidence of every state transition, and never allow callers to trigger new work simply by querying the current status.