e-mail shredder

An option (from Omniva Policy Systems) that lets users specify a "detonation time" of anywhere from 30 minutes to years after an e-mail is sent. The e-mail itself remains after the detonation date, but recipients who try to open it get only gobbledygook. The e-mail remains alive but the recipient must have a unique key to read it after the detonation time.

FYI: "Scrubbers" does the same thing for e-mail attachments and "anonymizers" masks the true origin of e-mail message headers.