From our experience, we needed to quickly find email adresses of people in a company, with an accurate return value, so we built Norbert : http://www.voilanorbe

From our experience, we needed to quickly find email adresses of people in a company, with an accurate return value, so we built Norbert : http://www.voilanorbert.com http://www.voilanorbert.com It's in it's early stage (if you go after 5 tries, you will be requested to pay via Paypal to enable unlimited access : it doesn't work so far). We don't plan to gain a lot of money on it, the limit is more to restrict user about abusing it. For information about how it works, it simply connect to the mail server, simulating a email to be sent, and testing if the server answer with a "Email not found" or "Ok". Depending on the answer, we know if this email exists or not.