Node.js function that will guess a persons email address given first name, last name, domain.

given first name, last name and domain, find a valid email. If there's an email found then it should return the email address. If it's a catch all address, then it should return "CATCH_ALL" To be hired for this job, you need to offer some expertise in this area and lay out a plan for how you will solve this. I'm looking for a resilient solution. Please advise if this requires multiple proxies. Requirement: You should be well aware of how email systems, relevant protocols work.