It does not make sense to get and instant e-mail noitifacton from yourself after you just created the task. I want to be reminded on the due date by e-mail.
2 answers
You need a workflow rule with 2 time based trigger:
Set Workflow rule to everytime a record is created or edited:
Time Trigger 1:
0 days after Task due Date and create an email alert.
Time Trigger 2:
'n' days after Task due date and and create an email alert
