Mail Relay Alerts

["Sean T. Ballard" <stballard () 4glschools com>]

I been getting thse alerts for a LONG time. Mail relaying from china9988 () 21cn com. I know this is a mass spam for a 
TON of other people get this same alert. My question is does anyone know whats actually causing this? Some kind of 
worm? Maybe a relay scanning tool that uses that as its defualt address? Someone satisfy my curiousty