EventGrid atleast one delivery paradigm

Author: ApnaLakshay

articles/update-manager/pre-post-events-common-scenarios.md

@@ -181,6 +181,11 @@ The system cancels the scheduled run if one or more of the following conditions
 ## Why the post event was not sent by the system?
 
 If the user modifies the schedule run time after the pre-event has been triggered, the post event will not be sent because the scheduled time has been replaced with a new one.
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+> [!NOTE]
+> Azure Event Grid adheres to an at-least-once delivery paradigm. This implies that, in exceptional circumstances, there is a chance of the event handler being invoked more than once for a given event. Customers are advised to ensure that their event handler actions are idempotent. In other words, if the event handler is executed multiple times, it should not have any adverse effects. Implementing idempotency ensures the robustness of your application in the face of potential duplicate event invocations.
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 ## Next steps