This utility performs a test to determine
whether it will relay third-party email. It will try to relay an
email message to yourself through that host. A host that allows
third-party relay is subject to attack by Internet vandals, and
frequently is hijacked by spammers to relay massive amounts of junk
email. A host that allows third-party relay should be immediately
secured, disconnected, or shunned as a menace to the Internet.