Re:Done before (Score 2)

Disclosure: I work for Disappearing Inc.

IMHO, it won't work, as people will either be forced to use a specific e-mail product, or there will be a high risk of the self-destruct system not working.

Any recipient with a web browser can read the email. The ciphertext is stuffed in an HTML attachment and decrypted at the DI website if the recipient doesn't have a DI-enabled client. Since the key is maintained (and destroyed) on a central server, the (poorly named) self-destruct system is not dependent on the client.

Even if the message DOES self-destruct, so what? You can scan a hard-disk and read off the last 10 or so layers of data, which might include the non-encrypted form, or the encrypted form with a valid key. From there, it'd be child's play to get the message.

Only the ciphertext is stored to disk. Both the key and cleartext are held in memory. There is a small risk that the cleartext (not the key) could be swapped to disk while the message is being viewed in a browser, but the swap file would be overwritten more than 10 times in a relatively short period of time.

There are far, far better ways to secure e-mail from prying eyes.

I assume you are referring to PGP and/or S/MIME. IMO, the big advantage to DI's approach is that it allows for temporary trust. To send you a traditional secure email, I must trust you to never reveal it to a third party, either maliciously, accidentally, or under duress (e.g. court order). To send you a DI email, I only need to trust you to not reveal it until the key is deleted.