how to capture responses when a responder drops out

how can a form capture responses when a responder drops out when filling a form.

I am not exactly sure if I get your question, you are probably wondering if you can get the submission data even if the email notification does not arrive, if that is your concern, the answer is yes. You can get all the data from the submissions view panel.

http://www.jotform.com/help/44-How-to-Export-Form-Data-to-Excel