https://learn.microsoft.com/en-us/dotnet/api/azure.messaging.servicebus.processmessageeventargs.deadlettermessageasync?view=azure-dotnet
ProcessMessageEventArgs.DeadLetterMessageAsync Method (Azure.Messaging.ServiceBus) - Azure for .NET...
Moves a message to the dead-letter subqueue.
methodazuremessagingservicebus