What added features will I receive if I upgrade to Contact Forms Professional?

The Professional Contact Forms service provides the following features:

-All advertising and branding will be removed from your service.
-You will have the added functionality of enabling file attachments to your form data (Maximum filesize is 10MB).
-You can turn off the interstitial page.
-Added benefit of being able to manipulate the markup.
-You can have a maximum of 50 form elements (questions) per form.