Creating Subject/Text in Submitted PDF

I've created a fillable PDF form using Pro X.  I'd like to program the Submit button so that once in the email portion, the subject line would automatically pull 3 specific fields from the PDF file.

Example:  After hitting "Submit"....once in the email, I'd like the Date, Vendor Name, and PO # from the PDF form to automatically pull into the Subject line.

I have to PDF the complete document and go through the Desktop Email Application on my PC.

Thank you!