You can certainly do that, but it’s often a lot of effort. Not sure it it’s worth it. Even when you narrow it down to one contact – it may not be that one contact at all, but something about his or her email provider, the path to that email provider or something else. It’s difficult (and inadvisable) to point fingers. On the other hand, it’s fairly common when signing up for mailing lists, or leaving comments on web sites that require an email address to use a specific email address to see if THEY end up spamming you. People use Ask Leo! – specific email addresses when leaving comments all the time. (And, no, I don’t spam ’em 🙂 ).