This article from NewScientist says spam, unwanted unsolicited email, counted for nearly two out of every three messages sent worldwide.
Fortunately, using two spam filters (SpamAssassin and PopFile), I never see the majority of it because I have SpamAssasin set to send it to dev/null. What spam makes it past there is filtered by PopFile and is automatically sent into a spam file where I can check it at my leisure. As noted in an earlier post, in a test of over 1,000 emails, the two filters were able to successfully filter over 97 percent of the drek.
Even MSN Hotmail, heretofore one of the bigger spam magnets around, has apparently instituted filtering. Such filtering is working very well and has cut down the number of spams getting through by at least 90 percent (just a guess but I think it’s pretty close).
So for me [knocks wood], spam is just not a problem anymore.