July 30, 2026
Every email validator — ours included — works the same fundamental way: we look up the mail server responsible for each address's domain, and we start the same conversation a real mail server would when trying to deliver a message: "Hey, do you have a mailbox for this address?" If the server says yes, that's a valid result. If it says no such mailbox exists, that's invalid. We stop the conversation right there — no message is ever actually sent to anyone on your list.
Some providers (Yahoo is a well-known example) accept the question for any address and sort out real vs. fake later — we call that a catchall result, and we tell you plainly when we can't fully confirm one so you're never left guessing what a result actually means.