Form was sent as a form, but message says only data will be sent, not form?

Just curious as to why, even though the form was transmitted via email, and the recipient received & saved the whole form, why does the email message have the auto message that the form itself is not being sent? I guess I shouldn't question it as long as the form is being received, but the testing thus far of the form has been internal between coworkers, so I'm concerned what will happen when the form is submitted outside of the current work environment.

Dropbox - Final_Financial_Report_CONACYT.pdf  -- <--------- Dropbox