It's this time of the year...
Outside the window it's snowing like a blizzard. Looks cool, especially as I have don't have to drive anywhere today ;-)
Inside my inbox it's raining mass-mailer worm messages. Stefan Bodewig is right: by sending back such messages to their (forged) From: addresses, virus detection software is only helping spread the plague.
SMTP is definitely too open for the wild Internet of today - hopefully something like SPF will come up before it's too late.