Error about "Send Exchange Mail Message"

Help Activities
,
1

Hi,my friends
I’m using it to do a test of sending emails in a loop. The first few times of the loop can be sent normally, and then an error The Autodiscover service couldn’t be located.
And next was the error message.
RemoteException wrapping UiPath.Mail.ExchangeException: The Autodiscover service couldn’t be located.
at UiPath.Mail.Exchange.Activities.ExchangeActivity`1.EndExecute(AsyncCodeActivityContext context, IAsyncResult result)
at System.Activities.AsyncCodeActivity.System.Activities.IAsyncCodeActivity.FinishExecution(AsyncCodeActivityContext context, IAsyncResult result)
at System.Activities.AsyncCodeActivity.CompleteAsyncCodeActivityData.CompleteAsyncCodeActivityWorkItem.Execute(ActivityExecutor executor, BookmarkManager bookmarkManager)