So you have a tool to find emails, something that scammers and spammers may use, and the first thing you ask on your website is for my email address?! How trustful is that?
Using emails that have been submitted to us through our signup form would obviously be a huge violation of privacy. We don't do this, and we never will.
You can view our privacy policy here https://maildb.io/privacy
Also, we are probably going to implement specific pages that allow anyone to delist their domain and/or email address from our service.