Can you prove you're not a machine?

Sounds like something out of "The Twilight Zone," doesn't it?

I've been thinking about something called the "Turing Test" lately because some of my personal e-mail has come back undeliverable. Evidently the servers, in an attempt to screen out machine-generated spam, think that my e-mail is spam, too.

1. Turing Test - The Turing test, developed by Alan Turing in 1950, is a test of a machine's ability to exhibit intelligent behaviour equivalent to, or indistinguishable from, that of a human.