On the subject of host security issues and spam, try doing a search of the Usenet archive for '"Net Access Corporation" spam'. You get 328 results. And those are just the spams which people have traced to NAC, never mind the millions of untraced ones....
The fact that their abusebot automatically forwards complaints to the
spammer^Wcustomer (even setting the 'From' address on the autoresponse
to the customer's address) may have something to do with this.