Isn't it pretty standard for website T&Cs to say something along the lines of "by uploading content to this website you are providing [website owner] with a license to reproduce the content"? Sometimes those T&Cs will be quite broad - non-revokable, across all media (including forms not yet imagined).

> The inability to revoke access is a failing of the tool or the product, not the law.

Does the law need to change? Or (in the case of email) is it fine as is because the reasonable person realizes that once you hit 'send', the content is out of your control?