Symptoms

K2 workflow not sending out emails
 

Diagnoses

We are working on a time-bound migration of a K2 application from MOSS 2007 to SP 2010 and are currently testing the application in our DEV environment. Until last Friday, we were receiving emails when we initiate workflows, but for some reason, K2 is not sending out emails this week.
 

Resolution 
The reason emails were not being generated is that the format of the destination user was incorrect. It was coming across as the display name instead of the account ID. The customer indicated that for audit purposes they could not use the account ID in the InfoPath form. We compared the functioning workflow in Production to the erroring workflow in Dev, and found that the wrong InfoPath field was being used as the Destination User. The customer changed this and attempted to redeploy and was met with a different error, which he resolved in another ticket. After a successful deployment, the email sent correctly.