A person's email inbox represents a great divide. It becomes very easy to judge how important a message is when it's sent via email.
If your message truly requires the attention of someone then perhaps email not be the best way to get it. That's not to say that email isn't at all useful. The fact that get's lost on the spammer is that the attention must be shared - the message must be as useful to the reader as it is necessary that it's read. Simply put, both parties must value one another.
Ironically, that must start way before you reach one's inbox.