#Line 21 of PayPal.pm (Business::PayPal)
address => 'https://www.paypal.com/cgi-bin/webscr' #change to https://www.sandbox.paypal.com/cgi-bin/webscr

#Line 82 of PayPal.pm (Business::PayPal)
        -action => 'https://www.paypal.com/cgi-bin/webscr', #do same as above comment

#Line 13 of IPN.pm (Business::PayPal::IPN)
$GTW        = 'https://www.paypal.com/cgi-bin/webscr'; # do same as above comments