Update delivery-and-retry.md

Added note explaining TTL and max attempts with respect to exponential retry schedule

Author: tomasszabo

articles/event-grid/delivery-and-retry.md

@@ -54,6 +54,9 @@ You can customize the retry policy when creating an event subscription by using
 
 For sample CLI and PowerShell command to configure these settings, see [Set retry policy](manage-event-delivery.md#set-retry-policy).
 
+> [!NOTE]
+> If you set both `Event time to live (TTL)` and `Maximum number of attempts`, Event Grid uses the first to expire to determine when to stop event delivery. For example, if you set 30 minutes as time-to-live (TTL) and 5 max delivery attempts. When an event isn't delivered after 30 minutes (or) isn't delivered after 5 attempts, whichever happens first, the event is dead-lettered. If you set max delivery attempts to 10, with respect to [exponential retry schedule](#retry-schedule), max 6 number of delivery attempts happen before 30 minutes TTL will be reached, therefore setting max number of attempts to 10 will have no impact in this case and events will be dead-lettered after 30 minutes.
+
 ## Output batching 
 Event Grid defaults to sending each event individually to subscribers. The subscriber receives an array with a single event. You can configure Event Grid to batch events for delivery for improved HTTP performance in high-throughput scenarios. Batching is turned off by default and can be turned on per-subscription.