Symptoms

We have a document library workflows where a couple of workflow instances that are not sending out any task emails. I can see that the tasks are created, but no emails go out. This is only happening on two specific files in the library. Now the only difference I noticed about those files are their file size, they are significantly larger than the others that are working.
 

Diagnoses

This issue was caused by MSMQ's size limit, which is used in client event notifications. MSMQ cannot process events totaling over 4MB in size.
 

Resolution

We explored the possibility of reconfiguring as email events, and ultimately found a workaround where we did not have to attach the content to the email by using the sharepoint rich text field to capture the needed data at entry, and embed it in an email using another workaround utilizing the sharepoint service v2 to preserve formatting of the message.