Symptoms

Permanent failure sending message New Task: System.Exception: No destinations could send the message New Task.
 

Diagnoses

When using a process that has email events, the actual event in the workflow is fired but no event notifications work in this scenario.

When looking at the even viewer you see the following errors:

Permanent failure sending message New Task: System.Exception: No destinations could send the message New Task.
at
SourceCode.MessageBus.Server.MessageBusRuntime.SourceCode.MEssageBus.IMessageDestination.Send(String title, MessageExtendedInformation extended, IEnumerable`1 attachments, MessageBodyReadere]messageBodies)

 

Resolution

To get around this issue you have to perform a reconfigure on the environment in question and confirm that the K2 service account had role based access on the service account on the exchange side (Online).

This should resolve the issue.