Agent went async but did not call Resume (Event Id 1057)
In Exchange 2013 you may see the following in the event log if you don't call resume in your asynchronous agent
Log Name: Application
Source: MSExchange Extensibility
Event ID: 1057
Task Category: MExRuntime
Agent 'Smith' went async but did not call Resume on the new thread, while handling event 'OnSubmittedMessage'
It is a best practice to call AsyncAgentContext.Resume() in your worker thread before doing any work to complete the event. This ensures that the thread is properly initialized for asynchronous event handling.