Let's start by defining the problem.
Despite the attempts of Anti-Spam Zealots to blur the meaning of the word "Spam" so as to apply it to a wide variety of perfectly legitimate email, there is a widely accepted understanding of what Spam really is. The following definition comes from SpamCop (one of the chief Anti-Spam Zealots) which does well to describe what Spam really is:
Spam is unsolicited bulk email. Not all bulk email is spam. Not all commercial email is spam. Email must be unsolicited and bulk in order to be spam. Unsolicited email is email the recipient did not (explicitly or implicitly) agree to receive. If the recipient agreed to receive it, then it is not spam.
Bulk email can be split into two categories: Opt-in and Opt-out. Opt-in is email that an individual requested or agreed to receive. Many legitimate mailers use opt-in methods for marketing. Individuals are responsible for reading and understanding a company's privacy policies and acceptable use policies (if applicable) before submitting an email address. If a privacy or acceptable use policy clearly states that signing up for the service results in receiving marketing or commercial email, then the individual has "opted-in" to receive email and that email is not spam. Individuals also implicitly opt-in for email regarding a purchase or transaction; for example, when buying an airline ticket via the web, the purchaser receives an emailed purchase confirmation, which is not spam. With opt-out email, the sender adds an email address to a mailing list without prior consent, then asks the recipient to request removal (or "opt-out") if he does not want to continue to receive email. Opt-out email is unsolicited and is by definition spam.
Unfortunately SpamCop (like most Anti-Spam Zealots) does not always follow it's own policies. And of course there are no regulations that require them to do so. (You can read more about this in the Anti-Spam Zealots section.)Spam is bulk email. If someone writes to an individual personally, one-on-one, to ask a question or inquire about a post made to a newsgroup or website, then that is not spam, even if it contains commercial or marketing content. However, email containing the recipient's name is not always legitimate. For example, if someone writes a personalized message, but fails to address any subject which is specific or relevant to the recipient ("Kelly, get the lowest prices on prescription drugs!" is an example), it is safe to assume the message is spam.