Throw away the Internet and start over?

[Justin Mason]

R. A. Hettinga said:

> I've talked for years about a simple modification of an old protocol,
> and have jokingly called it $MTP.
> In short, $MTP is: "friends mail me free, all others pay cash". 
> Unpacking the above sentence, we get:
> Friends:
> People on my cryptographically authenticated whitelist. 

What about:

  - spammers impersonating your friends, using forged To and Received
    headers?

  - your friends' mailing list, which sends mail as
    fork-bounces at lists.xent.com?

  - spam sent to the aforementioned list?

These ideas (cf. also hashcash, whitelisting in general) generally run
into those issues in SMTP -- namely there is no usable way to associate
a sender with an authenticated identity in current mail use, unless
you can persuade everyone to adopt S/MIME or PGP/GPG.

--j.