Re: MTS transparency and anonymity

On Sun February 27 2005 23:18, Keith Moore wrote:
> you'll get 
> an error, which is what we want to happen.

No, what we want to have is either a clear indication of lack
of an author mailbox (preferred, if practical), or a lack of
any indication of an author mailbox.
 
> > Yes, the loopback connection is supposed to be internal to the IP
> > implementation, and not be translated to any physical network.  That
> > still doesn't have semantics of "anonymous" or of "nonexistent"; it
> > has semantics of "here".
>
> in practice, it has the semantics of "nowhere", or "you can't get there 
> from here, no matter where 'here' is."

If I repeat Claus Assmann's experiment using 127.0.0.1 (the loopback),
what I get has semantics of "here".
 
> it's a backward compatibility issue.  MUAs and MTAs that know about the 
> convention are not the problem, since it's easy for them to recognize 
> such addresses and treat them accordingly. the problem is making this 
> work with MUAs and MTAs that don't know about the convention.

> hey, I'd be fine with anonymous@[ipv6:::0]
> 
> or perhaps even anonymous@[no-such-network:]

And the backwards compatibility of either is ... ?
 
> no, but it's the most important technical constraint on the convention 
> for an anonymous address.  see above.

"anonymous address" is an oxymoron.  "<>" (i.e. no mailbox) seems
less problematical (even with HTTP, SIP compatibility issues) than
some of the recent proposals.  At least "<>" has some sort of
precedent (in Return-Path).

> Too many things extract data from the From field.

If the field isn't there, they can't extract anything from it.
Less of a problem than extracting something and misinterpreting
it (or bombarding DNS with cruft, or misdirecting responses, or
crashing...).