On 6/29/16 2:30 PM, Michael J Wise wrote:
I will read up on it. Thank you for the link.
Not everyone, I think, who visits this list is an engineer.
In that you are mistaken.
Almost everyone who subscribes to this mailing-list is an engineer.
Please re-read that line.
This mailing list is for people who need to configure or make changes to
the configuration of a Mail Transfer Agent called Postfix.
Some people here actually suggest software changes, since the author of
the system is present on the list.
Pretty much everyone here is an engineer.
I could be wrong, but I expect that many of the folks here are NOT
engineers.
I happen to have an engineering background, and spend a good part of my
time doing engineering work of various sorts - but that's completely
incidental to running our mail system. As a one-man shop, I ALSO play
sys admin, postmaster, webmaster, listmaster, janitor, chief cook &
bottle washer, ad infinitum, ad nauseum.
I expect, that many of the folks here are full-time sys admins - a role
that does not necessarily involved (or require) an engineering background.
Having said that, it seems not unreasonable for folks on this list to
have a working familiarity with the standards and software associated
with email processing. Managing a postfix installation (or any MTA) is
not a job for amateurs. (IMHO)
AND NOW I'M CURIOUS... What kinds of backgrounds and roles do people
here have? Is managing a postfix installation part of your official
duties, or something that you've fallen into?
Miles Fidelman
RFC 821 (and its successors) is documentation of the COMMANDS (verbs, if
you will) used to move mail, of which one, MAIL FROM, is a way to express
where an NDR should go if something goes wrong.
Furthermore, at some points along the journey of a piece of mail (data, or
a NOUN if you will), it will be captured and recorded in a header, most
typically in the Return-Path value.
But it is not guaranteed to be stored in any header at any time because
it's a COMMAND to a server.
RFC 822 (and its successors) is documentation of the structure of DATA
(the NOUNS mentioned above) that represents an email message, which is
divided up into Headers and Data. One of those headers is, "From:". And
almost all of those headers are little more than comments, forgeable by
anyone with the inclination to do so, and at best advisory in nature.
So, to summarize:
The "From:" header is a comment, and may or may not reflect reality.
Typically it does, but not always.
The "Return-Path" is a recognized way to capture the value of the "MAIL
FROM:" command, and encode it into the headers, but it is best described
as a, "Virtual Header".
Some other headers inserted by arbitrary third parties are not documented
in *ANY* RFC anywhere, and almost everyone completely ignores them.
Such is the case with, "bounces-to".
It's not a standard.
Almost everything will ignore it.
People who expect it to always work should be prepared for disappointment.
Aloha mai Nai`a.
--
In theory, there is no difference between theory and practice.
In practice, there is. .... Yogi Berra
