what are sender emails

The sender email is the email address that shows in the email notification, by default the sender email in the notifications and autoresponders is noreply@jotform.com or noreply@formresponse.com , however you can customize it and make it appear the email notifiers as coming from your own email address.

Here are some guides for more help.

http://www.jotform.com/help/25-Setting-Up-Email-Notifications

http://www.jotform.com/help/238-How-to-Add-a-Sender-Address