Is it possible to reject a registration if payment is not paid?

Is it possible to reject/deny a registration if a payment isn't made?  A client is receiving a lot of pending registrations.  If rejection isn't possible, what have other users of JotForm been doing to solve the "pending payment" problem.

From what I understand on your form the user is not yet registered if they will not complete the payments.

Example:

Those in the Incomplete Payments box were incomplete submissions that were abandoned or payments were not completed.

Because the payment was incomplete, the Registration was not completed. So there is no need to reject/deny registration for those incomplete submissions.

Alternatively you can just delete the Incomplete submissions if there is not need for them.

Check the user guide: 

How to View Incomplete Payments

I hope this help. Let us know if you need further assistance on this.

An alternative option is to use Payment Authorization feature on your PayPal field.

How to Enable Payment Authorization

When this feature is ON, submission payments will always be sent to your paypal account.

You will then have control which payment to cancel or approve.

I'm sorry, maybe I wasn't clear.  Basically if a person doesn't submit their payment, I want them to receive an email to say that their payment has not been received. Is this possible? 

We are constantly getting people registering for the conference but not paying. Which means we have them in our list of registrants, which officially they aren't registrants.

Basically if a person doesn't submit their payment, I want them to receive an email to say that their payment has not been received. Is this possible? 

You can set an Incomplete Payment Email in the form. For the user you can send an Autoresponder Email even if they did not proceed to complete payment.

User guide: How to Setup Incomplete Payment Notification Email

Let us know if this will still not work for you.