Some lists try to fix this by abusing Reply-to: to try to steer discussion replies to the list address, but that is fundamentally broken.
About all you can do in a mailing list is to cull the junk from the permanent web archive.
[Edit: look, you can downvote all you like. I know how mailing lists work and stand by what I wrote. I have used mailing lists for almost a quarter century, and I run mailing lists of my own. I know the ins and outs, and ways they can be configured.]
Mailing lists are centrally managed, and have a "reflector" or central distribution point (what you call a "robot") which maintains the email addresses of all the people on the mailing list. In order to add or remove yourself to the mailing list, you typically have to send a message to name-of-mailing-list-REQUEST, not to the whole mailing list of course. Now days there are usually web pages that people can use to subscribe and unsubscribe and view the archives, and which the administrator can use to moderate messages, but in the old days the moderator was a human and administered the list via email. To save bandwidth (in the days that it mattered, i.e. over the slow ARPANET and over international connections and expensive dial up modems) there would be redistribution lists for regions and organizations, which users or local administrators would have to manage themselves (or the central administrator would have to forward requests to the redistribution list administrator), so only one copy of the message had to be sent to each redistribution list.
https://en.wikipedia.org/wiki/Electronic_mailing_list
An electronic mailing list or email list is a special use of email that allows for widespread distribution of information to many Internet users. It is similar to a traditional mailing list — a list of names and addresses — as might be kept by an organization for sending publications to its members or customers, but typically refers to four things:
1) a list of email addresses,
2) the people ("subscribers") receiving mail at those addresses,
3) the publications (email messages) sent to those addresses, and
4) a reflector, which is a single email address that, when designated as the recipient of a message, will send a copy of that message to all of the subscribers.
Traditional mailing lists (such as ones created by a vanilla install of GNU Mailman) do not work they way you describe.
They work like this:
1. You send a message to a mailing list address. This address belongs to a software agent which sends the message to everyone. Your From: header is clearly preserved. The mailing list robot adds itself to the Cc: line to stay in the loop.
2. Someone who wants to continue your discussion publicly hits Reply All. At this point, the mail software composes a a new message which To: you, From: this person, and Cc: to the mailing list.
3. You receive the message directly. The robot also receives it because it is in the Cc: loop, and sends it to the subscribers. (If you're also one of the subscrbers, and the list is configured that way, it will avoid sending you a "list copy").
4. And so it goes.
But what do I know; I have only used mailing lists for 25 years, and run mailing lists of my own on my own server.
I find it frustrating for a mailing list because invariably a long thread is going to have missing messages. In the context of a mailing list the default behavior should be to reply to the list and setting the Reply-To takes care of that nicely.
Btw, the "because I've been doing it for n years" argument gets less effective as n increases. Ok, it's probably a bell curve but it peaks long before 25.
My point is that an email message that has a bunch of people's addressed in it, but no central server or list of email addresses, which you reply to by copying all the addresses in the To: and CC: fields, is not a mailing list, no matter how sophisticated your email reader is. It's just an email message, and you're doing all of the work in your email reader. (Hello, Emacs!) That's not a mailing list. It's just an email message with a list of recipients. There's nothing preventing any recipient from adding or removing any address from the list, and there's no central archive or administration or moderation.
Here's what mailing lists looked like in the 80's:
http://its.svensson.org/.MAIL.%3B.MCNEW
Who remembers Mark Crispin's oft-repeated catch phrase, "MM is not at fault!"
JWZ's Law of Software Envelopment: Every program attempts to expand until it can read mail. Those programs which cannot so expand are replaced by ones which can.
So are you! Your original point hinges entirely on having many non-centralized posts and counting them as part of the list.
Counterexample to your claim: browse the linux kernel mailing list archive at https://lkml.org/
On any message you can click [headers] to view the headers. You can see rich Cc: lines full of addresses. Well, you can't see the addresses because they have been scrubbed. But you can count the commas! For instance:
Cc: Rusty Russel <>, , , , John Smith <>,
For instance, exhibit A:
https://lkml.org/lkml/mheaders/2014/9/30/320
Note how "Kernel Mailing List <>" is on the Cc: line, too.
All of the mailing lists that I operate on my own mailing list server allow non-subscribers to post. Due to my anti-spam configuration, this isn't a problem.
Traditional mailing lists, before the rise of spam, were usually this way.
And anyway, this is a separate issue. A list which does not re-mail postings from non-subscribers can nevertheless not do Reply-to: munging. So once you are on the list and participate in discussions, you're still sending messages to the list, as well as directly to those in the discussion.
Earlier this year I was involved in a mailing list discussion in which one of the parties was actually (unbeknownst to me for a while) a "persona non grata": someone banned from posting to the mailing list. His postings were not being seen by the subscribers, but only those in the debate. This list does use Reply-to:; he just (trivially) circumvented it.
How mailing lists operate is constrained by how e-mail works. E-mail is very conservative.
(Yes, various things are there that weren't there a quarter century ago, like parsing out MIME-attached HTML and rendering it. Sure, SMTP is optionally authenticated and encrypted now. And in the routing and delivery infrastructure we have things like DKIM, SPF and DMARC. And we have DNS-based anti-spam databases. But by and large it's the same. The way a client sends and receives has not fundamentally changed.)
E-mail is a mine-field for people who think they have some great idea about some quick fix to a perceived problem.
About fifteen years ago, it seemed---to multiple people at the same time---like a brilliant idea to write an extension for a mail client (or a procmail script or whatever) to automatically answer all e-mails from senders who are not on a white-list, and challenge them to verify that they are real. That would solve all forgeries and spams, they thought! Oops ...
Reply-To is a special header that is normally not present.
It has a valid use case (what it is designed for). It's used when someone composes a message on behalf of someone else (like a secretary on behalf of the boss). It says that another person is the real author; please reply directly to that person.
When it's added by a mailing list robot, it wrecks the traditional operation of the mailing list.
For one thing, it becomes hard to reply privately. You hit "reply", and the message is composed to the mailing list.
A mailing list non-subscriber is not able to get a reply to a question posted to a mailing list. So the Reply-to trick is only compatible with subscriber-only mailing lists, which are a pain in the butt.
Reply-To is a wrongheaded solution to a mailing list problem: and that problem is people using "reply" instead of "reply all", generating private discussions that do not go to the list, but unintentionally.
Today, a feature is showing up in mail clients (at least open source ones): "reply to list". This addresses the problem in a better way. The mail client recognizes, from the headers, that the message being replied to is a mailing list item, and presents this clear way of replying. Furthermore, the mail client extracts the correct list address from the headers.
Unfortunately, "reply to list" implementations are still not kind to non-subscribers. The feature assumes the subscribe-only style of mailing list. (What is needed is a list header by which the re-mailing robot can tag the message as being from a non-subscriber, so the mail client can know to keep that person in the loop.)
Also, the direct, back-channel replies sent among participants do not carry the list headers, so "reply to list" does not work for those: it's back to "reply" or "reply all".
"'Reply-To' Munging Considered Harmful" is twelve years old, and I don't think the list of mail clients containing "reply to list" includes any of my favorites - much less making it the default, as it should be, since at least on the mailing list I manage, it's an extremely niche case to want to reply to someone privately.
And if you do so, you run the risk of the recipient not noticing the To header and thus getting confused about whether the message was private or not - especially in the many modern clients that use a linear rather than hierarchal view of threads, where you'd end up with a "conversation" randomly interspersing private and public parts. Much better to just compose a separate email.
> Unfortunately, "reply to list" implementations are still not kind to non-subscribers. The feature assumes the subscribe-only style of mailing list. (What is needed is a list header by which the re-mailing robot can tag the message as being from a non-subscriber, so the mail client can know to keep that person in the loop.)
Allowing non-subscriber threads using "reply to all" is a fundamentally limiting feature, though.
- The most important point: if you're not CCed by someone else, you have to start a new thread; if you are browsing archives, you can't just 'forge' a reply to a message you didn't receive, or at least I haven't used a client that lets you do this. And you should be browsing archives, because the alternative is asking questions without knowing if 10 people have asked the same thing recently. If you are CCed, you only get replies strictly hierarchally located under yours; you can't really join the discussion as a whole.
A better system would allow you to join a thread at any point and start to receive followups sent anywhere in that thread (but only that thread).
- In lieu of such a header currently, or in case of clients which don't support it, if someone does reply to the list, you will silently be cut out of the loop.
- There's no way to stop receiving reply-alls. Not the end of the world, since even Gmail lets you mute conversations, but it's more clunky than necessary.
In my ideal system, all mail would be forwarded through the robot so you're cut out of the loop iff you want to be.
- Not as "fundamental", but there's no guarantee the list in question even has a usable archive browsing interface. (I don't pay enough attention to which interface I'm using to name names, but there seems to be a common archiving UI which does not wrap messages - of course they should be sent wrapped, but in practice I've often seen one-line-per-paragraph messages.)
For the record, my ideal system is somewhat approximated by Discourse, which is a forum, but gives you the option to receive all messages as email and reply via email. However, there are various implementation defects which make me not really want to promote it.
4.4.3. REPLY-TO / RESENT-REPLY-TO
This field provides a general mechanism for indicating any
mailbox(es) to which responses are to be sent. Three typical
uses for this feature can be distinguished. In the first
case, the author(s) may not have regular machine-based mail-
boxes and therefore wish(es) to indicate an alternate machine
address. In the second case, an author may wish additional
persons to be made aware of, or responsible for, replies. *A
somewhat different use may be of some help to "text message
teleconferencing" groups equipped with automatic distribution
services: include the address of that service in the "Reply-
To" field of all messages submitted to the teleconference;
then participants can "reply" to conference submissions to
guarantee the correct distribution of any submission of their
own.*
3.6.2 Originator Fields
... When the "Reply-To:" field is present, it
indicates the address(es) to which the author of the message suggests
that replies be sent.
Also, the "Sender" header is meant for the example you gave (composing and sending an email on behalf of someone else), not Reply-To.