I believe that there was a bug logged for this issue, here is a workaround.
Add a regular button to the form used to execute the EmailSubmit button (you can make the EmailSubmit button invisible)
On the click event of the "newly added" regular button add your script
NameOfEmailSubmitButton.event__click.resolveNode("#submit").target = "mailto:"+customemail.rawValue+"?subject="+subject.rawValue+"&cc="+cc.rawValue+"&bcc="+bcc.rawValue+"&body="+body.rawValue;
You can probably do the same for a regular submit button action URL. But, this may prevent Reader users from submitting the form, when the client side e-mail software fails to open or is non-existant (Web mail).
Instead, you should submit to a server-side script, and handle the PDF form submission and e-mail through a SMTP server, bypassing 3rd party e-mail software such as OUTLOOK.
If you're using an ASP.net web server, then check out www.PDFEmail.net
PDFEmail.net creates the scripts and libraries for you. All you need to do is upload the script and libraries to your web server root or application directory, and point the PDF submit button action to the URL of the script.
PDFEmail.net can parse and populate a Email address from a PDF form field. Plus you have full control over the Subject, Body, TO, CC, BCC. Check out the online demo:
There is no programming necessary, but the scripts can be modified. For example: submit, email, and save to file server or database. Works with Adobe LiveCycle and Adobe Acrobat PDF forms, and in standalone Reader and browser served PDFs.