You need to submit using Adobe JS Actions; such as, mailDoc. There are multiple JS functions that perform similar actions. Using Adobe's built in Js functions requires client-side email software. JS is the least reliable way to send forms; because, not every user has their email software setup correctly.
Another way is to submit to a server-side script; such as ASP.net. The script can send the form submission without client side email software. Using iText; you can parse the form field text box and inject it into the mail message TO field. You can also pass the script a TO: email address in a URL query string parameter and when the form is submitted.
Note: Either way; the end-users will need Adobe Reader or a compatible PDF Reader in order to submit the PDF forms.
For online examples visit the following website: