Internet threats have historically been classified as real threats from hackers and virus writers, and then the second order issue of time wasting caused by non-business internet browsing and by having to deal with spam.
The problem of spam hardly needs an introduction. It is a time-waster for recipients. It has its sinister side in the form of V-spam and phishing. And it consumes infrastructure resources -- especially bandwidth. The only real solution available today is blocking: either at the recipients' premises or, sometimes, at the recipients' ISP. But this feels very much like locking the stable door after the horse has bolted and there must be a better alternative.