> --On Thursday, March 05, 2009 13:05 -0800
> [email protected] wrote:
> >...
> > That's wasn't Tony's point. His point was that Sieve breaks
> > the RFC 5321 rule
> > by allowing scripts to assign whatever semantics they like to
> > local parts of
> > external addresses. Sieve can be case-sensitive or
> > case-insensitive (the latter
> > is the default) and even has an extension for extracting
> > subaddress information
> > from arbitrary addresses.
> Ned,
> I think whether Sieve is complaint or not depends, as all of
> these things traditionally have, on how you model the delivery
> process and its relationship to it.
Sieve is specified as occuring around the time of final delivery. If it is
applied just before final delivery, that puts it in the scope of SMTP.
> If I hang Sieve off of a relay in the middle of the network and
> then start parsing and interpreting local parts, it would
> clearly be non-compliant, but, to a certain extent, that status
> is a definitional contradiction: a thing in the middle of the
> network with a Sieve processor hanging off of it and
> interpreting and acting on local parts (or any of several other
> things), isn't a relay any more.
It isn't a conforming sieve implementation either. As such, while I suppose you
could implement such a thing, I see little point in discussing it.
> Whether it is a gateway
> between logical spheres of administrative influence, a "final
> delivery" SMTP server at the boundary of some domain that has
> its own internal mail classification and routing machinery, or
> some other sort of odd beast is a separate question --one that
> I'm not sure we improve the world by trying to answer-- but it
> is definitely not a 5321-conformant relay whether it interprets
> those addresses case-independently or not.
And by the same token neither is an autoforwarder that performs
an authorization check on the MAIL FROM address by comparing
it in a case-insensitive way with a authorized address list.
So is this a gateway too? It doesn't meet the definitoin in RFC 5321 - it's
certainy not passing messages between different transport environments. But
let's ignore that for now. Suppose it is a gateway. You've just reclassified a
significant fraction of the relays out there as being a gateway. Those are now
joined by the ones that apply Sieve prior to final delivery, agents that employ
various sorts of white and black list technologies, and lots of other stuff.
Travel much further down this path and the pure relays RFC 5321 spends so much
time on aren't endangered, they're essentially extinct.
> If the Sieve process is either beyond whatever one considers to
> be the final delivery server or is acting, with authorization,
> on behalf of that server or a user beyond it, the 5321 rules are
> really not being violated.
> All of this was a lot more clear when mail was delivered to an
> SMTP server at the boundary of an enterprise which then
> proceeded to interpret the addresses, rewrite the mail, and
> deliver it using mail protocols that didn't work on the Internet
> backbone. Those days are, fortunately, long gone.
In fact with the advent of complex webmail systems, one can argue that these
things are more popular than the various LAN email systems ever were. But
that's really a different discussion for another day.
Ned
