(this post was written using a SharePoint online environment and SharePoint Designer 2013)
So here’s the scenario, there is a central list where users add items and once submitted a workflow runs that assigns tasks to separate task lists. No big deal right?
The scenario
Task actions in SharePoint 2013 workflows are a pretty standard thing, the example above just assigns tasks to different lists (think HR, IT, Pensions) for work to be completed. The additional requirement I had was for these tasks to not send any system generated assignment emails when the tasks are assigned.

The problem
This one really had me pulling my hair, but in a nutshell there is no obvious way to turn on/ off the emails that are system generated at the point which a task is assigned.
When you double-click on a task, an “Assign a Task” window opens. Within this window there is an “Email options” drop down, but this only has the email editor for the task creation email and the ability to turn on/ off the task overdue email(s). It doesn’t have any settings for switching on/ off the initial emails themselves.

The hidden task properties pane
So at this point I began thinking there is no way to do this and the design for this process is now fundamentally flawed…until I right-clicked!
If you right-click on the list within the assign task action (the ICT Task List Members bit underlined in the example below) a menu will appear. Normally this menu contains some simple options like moving an action up or down. However, with task actions there is an additional option called “properties”.

After clicking on the “Properties” button, you’ll find an additional “Assign a Task Properties” window which contains the following, hidden properties:

- PreserveIncompleteTasks: set to true if you want non-completed tasks to be deleted when the task process is complete.
- WaiveAssignmentEmail: set to false if you want to have an email sent out to the assignee when a task is created
- WaiveCancelationEmail: set to false if you want to have an email sent out to the assignee when a task is canceled.
By default, all of these properties that are set to “no” or “false”, so will send emails based on the above parameters. To change, just click on the drop down next to each option and update to “yes” or “true” and the emails will stop sending!