Alan Clegg <[EMAIL PROTECTED]> wrote:
>
> > The particular assumption that Charles didn't explain is that
> > user%host2&host1 or host2|user@host1 will be relayed by host1
> > to user@host2.
> If anyone cares, this used to be completely legal and actually, a very
> useful way of doing things. There were a number of UUCP sites that were
> much quicker to address via:
>
> [EMAIL PROTECTED]
>
> than giving the full ! path to the actual uucp site. This was not "broken",
> it was "operational".
The brokenness comes from a third party looking at the local-part of that
address, and deducing that it implies relaying. The most recent SMTP RFC
(2821) forbids this in section 2.3.10:
The standard mailbox naming convention is defined to be "local-
part@domain": contemporary usage permits a much broader set of applications
than simple "user names". Consequently, and due to a long history of
problems when intermediate hosts have attempted to optimize transport by
modifying them, the local-part MUST be interpreted and assigned semantics
only by the host specified in the domain part of the address.
Prodygy (or whoever it was) was assuming that since a qmail server responded
with a 2xx code to
RCPT TO: <[EMAIL PROTECTED]@baz.net>
that it would relay the mail. That assumption is incorrect, and has always
been. The fact that some sites will interpret the local-part of that address
and relay it does not mean that all sites which do not respond with a 4xx or
5xx code to that command should be identified as relays.
> I guess those days are gone, however.
So are the days of the 5-cent Coke and the sub-$1000 new car. Doesn't mean
I'm wistful about them.
Charles
--
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Charles Cazabon <[EMAIL PROTECTED]>
GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/
Any opinions expressed are just that -- my opinions.
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