Is it broken ? I configured the email and set "test mode", i.e. PAYPAL_DEBUG, however I'm being redirected to the regular paypal site, not the sandbox.
I've read the sticky post, but I don't understand - is Virtuemart being distributed with non-working paypal configuration !?
Have you changed the URL in the PayPal payment module? You can find this in the configuration tab, at the bottom, under "Payment Extra Info"? If you are testing with the PayPal Sandbox then you need to change the default URL (the real PayPal site) to the Sandbox URL:-
$url = "https://www.sandbox.paypal.com/cgi-bin/webscr";
You will of course need to change this back to the URL of the real PayPal site when you finished testing.