At 10:12 AM 2/2/2001 -0500, James M Galvin wrote:
I called it illegal because a localpart should be opaque outside its
local environment. I tried to find a reference to this effect in some
standard but couldn't. It may just be "practiced wisdom" but I can not
remember a time when it wasn't true.
MUST be opaque, not should be.
Not only has it always been true, but it has usually caused problems when
violated.
The language in RFC822bis
<http://www.ietf.org/internet-drafts/draft-ietf-drums-msg-fmt-09.txt> is
definitive, though not as obnoxiously forceful as seems to be needed, to
make the point for this thread:
3.4.1. Addr-spec specification
...
The local-part portion is a domain dependent string. In addresses, it is
simply interpreted on the particular host as a name of a particular
mailbox.
Firewalls and proxies are exceptions that I personally explain in terms of
their being authorized on behalf of the "particular host". There is some
operational fantasy to that explanation, given that the agents are
typically operated by a different group than the ones running the email
user software, but it is the real theory that such agent services work on.
That it, such agents are part of a common administrative domain which
authorizes their messing with the data.
Stray relays and services that are out it the great beyond of the general
Internet are NOT so authorized. They are MUCH more likely to interpret the
local-part incorrectly
d/