Don't use the 'Email Submit' button but the simple 'Button'. In the button's object properties, in the tab named 'field', select 'Control Type: submit'.
Then, in the 'submit' tab, which miraculously appears in the object properties, choose PDF in the 'submit format' dropdown field.
In the 'submit to URL field' type:
> mailto:name@address.com?subject=mySubject&body=here-we-go!
You may want to adjust the e-mail address, subject and body text. :-)
In order to be able to submit PDF, you have to 'unlock' the form using Adobe Reader Extensions (Server), I think.
Regards,
Steve