Take a look at, for example, "Abuse at Scale" from the Gmail folks at April's RIPE conference for an idea of the threat. https://ripe64.ripe.net/presentations/

Take a look at, for example, "Abuse at Scale" from the Gmail folks at April's RIPE conference for an idea of the threat. https://ripe64.ripe.net/presentations/48-AbuseAtScale.pdf https://ripe64.ripe.net/presentations/48-AbuseAtScale.pdf 1 million+ bogus authentication attempts per day, 60-100k auths per second (legit and not), etc.