Do you have SharePoint? If you have SharePoint you could use SharePoint workflow to do this. If you don't have SharePoint you could look at submitting your form to a DB (like SQL) and then you could enable email on your SQL server and setup emails to be sent out at the right time. There isn't anything builtin to InfoPath iteslef to allow this sort of funciton though - it would require a secondary solution of some kind to get it to work.