Reply To: Not receiving IPN

When I’m testing I set it to “Sandbox” mode with the e-mail for PayPal Sandbox account , and I’m logged on my PayPal Sandbox account on the same browser, as PayPal requires.
It is possible that going live may fix the problem, but for obvious reasons I would like to be able to test the system before going live.
It’s possible that I’m missing something on the PayPal Sandbox configuration?, what are the steps to set everything right?