Symptoms

Emails are generating the error: SourceCode.Workflow.Common.EWS: The response received from the service didn't contain valid XML

Client event notifications are sending twice.
 

Diagnoses

This error can occur when access to EWS is restricted, so K2 does not get a valid response.
 

Resolution

- Add an SMTP connection string using the Connectionstringeditor.exe at aINSTALLDIR]K2 blackpearlHost serverin

- Change the K2HostServer.exe.config file (located in the same directory) to use instead of

- Restart the K2 service