Ah okay. Then I think you have no other choice but...
Put a button to your form and select edit code to write your own code:
First thing you need to do is use the thisXDocument.SaveAs() method to temporary save your infopath form to C:\temp on your local disc for example.
After that you can use then the MailMessage object to achive what you want, you need to add the attachment of course. should be something similar to this:
MailMessage mes = new MailMessage();
mes.From = "[email protected]";
mes.To = "[email protected]";
mes.Attachments.Add("C:\\temp\\yourForm.xml);
Keep in mind using the SaveAs method requires your form to be set to full trust.
Give it a try hope it'll work for you. Let me know if it helped.