[lattejed]

Without giving too much away, how does this work and / or how reliable is it?

I was actually looking around for <famous VC>'s email and it produced one for me.

[giordanobd]

If it produces an email it is pretty accurate. It checks various possibilities, and returns the valid ones. If only one is returned you can be pretty sure it is a valid email. You can use the social links to see if the email is associated to a facebook / twitter account.

It does check that the domain is not "catch-all", or that it doesn't simply ignore our queries.

[lattejed]

Yeah, it returned exactly one email that's likely (in my opinion) to be correct. That's really cool. Thanks.

[ffumarola]

It probes the MX records.