Every method of finding an address is either observation or inference, and the difference decides how much you can trust the result. A published address is a fact. A pattern applied to a name is a hypothesis that a mail server has to confirm.
That confirmation step is where most workflows fail. Of the 383,368 addresses we analyzed through live SMTP verification, 23.9% came back invalid, and a large share of those were pattern-generated addresses that looked correct and were never checked.
The guides here cover finding addresses by domain, by role and by permutation, and the specific research paths for founders, HR managers and recruiters where public signals differ.