@Hari Prathipati Thanks for reaching out. Currently it is not possible to create an alert when a message is dead-lettered in azure service Bus. you can create one that fires when you have messages in your Dead letter queue. You should then remove the message from the DLQ which will resolve the alert.
Select Alerts
and Alert rules
in the Azure portal, click Count of dead-lettered messages in a Queue/Topic and create alert.
Alternatively, you can create an Azure Function with a Service Bus trigger or a Logic App that is triggered when a message is dead-lettered and then configure the function or logic app to send an email or perform any other custom action that you want.
do let me know incase of further queries, I would be happy to assist you.
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