...target_task_name = DummyTask83...
You should go through OOTB PLC workflow. In this workflow you will find task for sending emails.Here URL Task has been used to send emails. You can take inputs from here. This makes easy for you. One thing make sure, two predecessor links of email task should be like:default: Task Name + Successtimeout: Task Name + TimeoutThat is defined in PLC workflow.Hope this help !!
Since there was no mention of SitePublisher or LiveSite in the original post - why would you recommend use of the PLC workflow which is specifically designed for SitePublisher/LiveSite?
You should go through OOTB PLC workflow.
So....you're not recommending it?