I believe it would have been helpful for the article to clearly distinguish between SPAM filters and SMTP mail filters such as Spamcop and Spamhaus. Having important e-mails flagged as SPAM is frustrating - or worse if you don't review them - but loosing incoming sales enquiries or outgoing order dispatch notices and invoices is intolerable. I've seen instances where a well known ISP has blindly used a SMTP mail filter which inadvertently included its own servers!
I am of the opinion that interfering with the delivery of e-mail should carry the same penalties as interfering with the deliver of paper mail/post. IMHO its rather arrogant to think that those who develop SPAM detection software are cleverer than those who send SPAM. Conceptually it seems so simple to verify the server that sent an e-mail (and for it to know its legitimate addresses). Perhaps the real conspiracy theory applies - fixing the problem is a one time fix rather than a constant revenue stream for software developers.