Question: How to configure Paypal payment gateway in HC panel? 
 
 Solution: 
    Login as "hcadmin" then click Billing System :: Integrate Edit/Payment Gateways (Paypal).
 
    Set Gateway URL as: https://www.sandbox.paypal.com/cgi-bin/webscr (Switch Gateway in Test Mode)

    Set Gateway URL as: https://www.paypal.com/cgi-bin/webscr (Switch Gateway in Live Mode)

Now Login to your HC Panel and provide paypal merchant information at this path: Billing System :: Manage Billing :: Configure Payment Gateways :: Configure Gateway. Here is the brief explanation of different required filelds at above path:

     • PayPal Email Address: Provide your Paypal merchant account email address.

     • Command Type:  _xclick
       It is recommended value because normally this Command type is used for online purchasing.

     • Set Send IPN= NO
       & IPN URL= Blank (Leave this field Empty)
       If you don't want to define IPN URL in hc panel and want to use same IPN URL provided in Paypal interface.

     • Set Send IPN=YES
       & IPN URL= http://www.YourDomain.com:8787/BillingManager/PaymentResponse.aspx. HC will redirect you to this IPN URL after the payment.

     • Set Send IPN=YES
       & IPN URL= (Leave this field Empty)

     HC will automatically pick the URL from your browser address bar and will redirect IPN on it.