Email Verifier

A mail server's agreement to accept a message proves nothing by itself: some domains are set up to accept mail for any address. Such a server will say "yes" even to a made-up mailbox.

So the tool asks a second question, about an address that is known not to exist on the same domain. If that one is accepted too, the answer says so: the domain accepts everything. That is not the same as "the mailbox exists", and the tool does not pass one off as the other.

There is no bulk checking here on purpose. Servers treat mass mailbox lookups as list building and put the asker on spam lists. After that, the check would stop working for everyone.

Keep in mind that a domain and a mailbox are different things. A label about free email or a disposable service describes the domain and does not answer whether the specific address lives on it.

The tool does not always get an answer. Some servers reply the same way to any question, some stay silent, some take longer than the tool is willing to wait. In those cases it says there is no result instead of guessing.