Re: Scope for self-destructing email?

[Phillip Hallam-Baker <[e-mail]>]

On Thu, Aug 17, 2017 at 9:30 PM, John Levine <[e-mail]> wrote:

> In article <[e-mail]> you write:
> >This is an interesting idea.  For those of us who deal with many emails,
> >(particularly upon return from vacation), not having to deal with lunch
> plans
> >that have expired would in fact be nice.
>
> See RFC 2156 and RFC 4021, section 2.1.50.  To me the interesting
> question is why, since we've had Expires: for 20 years, nobody uses it
> outside of netnews.
>
> > That's a job for good-old-Usenet Supersedes:,
> >but that's one email overcoming another, and the whole thing needs
> >some cryptographic support.  Note that a merkle hash (a la s/key) would
> >probably suffice.
>
> Seems like overkill.  How about you pay attention to the Supersedes:
> (see RFC 2156 and RFC 4021, section 2.1.46) if old and new messages
> both have DKIM signatures from the same domain?  Same question about
> why after 20 years nobody uses it outside of netnews.
>

​DKIM almost helps but this is a data level feature and it really does not
work well with a presentation layer authentication scheme like DKIM.

And to make it work well, you have to start from a messaging infrastructure
where every message and sender can authenticate themselves
cryptographically from the beginning...​