[jeffgrant]

Short answer, no.

There ARE some methods that may be successful, but they depend on a few things (like image linking, for example, which relies on the mail reader loading images, etc), and cannot be relied on.

Even a read-receipt cannot be guaranteed... for instance, I never send them, even when requested.

EDIT: If you control or have administrative access to the other person's email server, you could tell whether or not the email was downloaded to them, but even that doesn't necessarily mean that they read it. It could have been split off as spam, etc.