funsec mailing list archives

Re: netiquette argument of the month


From: Gadi Evron <ge () linuxbox org>
Date: Tue, 13 Jul 2010 13:16:08 +0300

[top-posting]

Thanks for your informative post, Rich. Interesting. It puts some 
interesting light on the issue.

I have to tell you though, even if I accept all your reasoning, I still 
dislike the notion as it just seems snobbish behaviour to me, which I 
don't like. I prefer blunder to attitude.

        Gadi.



On 7/12/10 2:40 PM, Rich Kulawiec wrote:
On Sun, Jul 11, 2010 at 02:13:51AM +0300, Gadi Evron wrote:
Mail clients handle dups well, as do mailing lists. Two layers of
protection again the horrible double messages.

Ah, but it's not quite that simple, unfortunately.

The proper way to filter (or file) mailing list traffic is via
RFC 2919's  "List-Id" header.  The funsec list is run via Mailman,
which automagically inserts that header unless overridden by the
list-owner, so all messages traversing the list carry it.  Off-list
replies to on-list messages don't -- and shouldn't.

Which means that anyone who is correctly dealing with funsec traffic --
that is, using the List-Id and not the subject-line tag (a bad idea in
itself, but let's gloss over that for the moment) will likely send
on-list traffic to one file/folder, and off-list traffic to another.
So given that duplicate messages arrive asynchronously and are disposed
of differently, duplicate detection is something that a mail client
is not likely to be able to handle.

In addition: modern mailing list mechanisms (like Mailman) permit
subscribers to join lists from multiple addresses and to set a "nomail"
flag on any or all of those.  It's not uncommon for subscribers to use
this to receive of list messages at one address but to gain posting privileges
from another.  (Since nearly all mailing lists don't permit, or at
least don't permit with owner approval, traffic from non-subscribers.)
Thus there is no way for any other subscriber to know that "the address
that onlist messages from subscriber S come from" is also "the address
at which S receives list traffic".   And of course if they *do* differ,
than duplicate replies will result in mail to different addresses,
possibly on different servers and handled by different mail clients.

And in addition to that, there's the hairball of SMTP filtering,
including greylisting and other mechanisms: since the duplicate copies
originate from different hosts on different networks, there's no way
for senders to know if they'll be treated differently.  A subscriber
may have exempted linuxbox.org from greylisting but not other subscribers'
outbound mail relays, so it's quite possible for on-list messages to
arrive considerably in advance of off-list duplicates.  Or vice-versa.
The same is true of other SMTP filtering mechanisms in the path,
which may or may not handle both copies the same way, and some of which
may or may not be under the control of subscribers.  (While it's likely
a safe presumption to guess that subscribers who *do* control those
mechanisms have taken steps to ensure delivery of on-list traffic, it's
not a safe presumption to ensure that they've done the same for off-list,
especially since there's really no way for the to know where it's going
to come from.)

What *most* mail clients do not do is handle reply-to-list well
(practical + non annoying).

Well, true, but I think that argues for choosing a better mail client
or for modifying the current one (whether via configuration, if possible,
or code, if necessary).

Any decent mail client will present the key headers (From, To, Cc, Bcc,
Subject, Reply-To) for editing so that senders can appropriately modify
all of them (or not) before sending.  Thoughtful and clueful senders
will take into consideration proper netiquette and deal with them,
as much as they'll trim quoted material or take other steps to minimize
not only the total mail traffic, but the inconvenience to recipients.
And that last is what proper netiquette is really about: being frugal
with the use of others' resources, especially their time.

---Rsk
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-- 
Gadi Evron,
ge () linuxbox org.

Blog: http://gevron.livejournal.com/
_______________________________________________
Fun and Misc security discussion for OT posts.
https://linuxbox.org/cgi-bin/mailman/listinfo/funsec
Note: funsec is a public and open mailing list.


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