Quoting Steve Litt (slitt@???):

> Hi all,

All: OH HAI!

> There's been some discussion about whom to reply to. I guess it's a
> personal preference, and my personal preference is described in the
> remainder of this email...
>
> If you want to reply to me, on-list, please reply to the list only.

You can ask, but it's mostly futile because most people's software
doesn't handle mailing lists intelligently. Exceptions include mutt
(which I use) and emacs GNUS. Both of those have a (configurable)
ability to do list-mode replying, in which the MUA trims out
non-mailing-list addresses, whenever the user does a group reply that
includes a mailing list address. (I'm being a bit inexact. The details
are IMO not worth detail-freaking to death.)

Point is, though, that -- generally speaking, with very limited
exceptions -- an MUA[1] offers a choice between two things, Reply-Sender
(often labeled just 'Reply') and Reply-All. Reply-Sender in an
RFC-compliant MUA generates a reply to the Reply-To address if
specified, or to the sender address if not. Reply-All generats a reply
to all addresses, period.

An unusually smart mailer (mutt, GNUS) is, as mentioned, able to do
group replying incrementally better by starting with a Reply-All
recipient roster and prune out all addresses that aren't detected to
be mailing lists. This also has benefits for any downtream replies, in
that they receive a pruned roster. Thus, every mailing list needs more
mutt and GNUS users; we improve things for everyone else. Gestures of
appreciation in the form of Bordeaux grand crus will be gratefully
accepted. ;->

Anyway, the reason your request is futile is that everyone responding to
your public postings _except_ mutt and GNUS users, in order to make you
happy, are being implicitly asked 'Every time you group-reply to one of
my mailing list posts, please take the time to manually delete me as a
direct-reply recipient from your draft post's headers. KTHXBYE!'

And, people just aren't going to bother, unless perhaps you put them on
monthly retainer to motivate them to do so. ;->

However, if you're sure you want to suppress direct replies because they
duplicate the mailing-list-routed copy, there's a solution that's been
standard since God was a teenager. Quoting ~/.procmailrc:

:0 Wh: msgid.lock
| formail -D 8192 msgid.cache

This detects dupicates based on Message-ID headers by comparing against
a cache of recent mails' headers, and discards additional copies after
the first one. So, if you get sent both a direct and a
mailing-list-routed copy, procmail will keep whichever arrived first and
autodiscard the second.

If you aren't using procmail as your LDA, then you're on your own, but
I'd expect any local delivery agent to be able to solve this
bog-standard problem. If it can't, find a better one.

I'm not aware of any easy way to ensure that one of those is LDA-chosen
to be retained and never the other (or chosen by the MUA, or whatever),
but I've not really tried to solve that problem.

FYI, some not-Steve Litt people are adamant that they're really
unhappy about _ever_ getting both direct and non-direct copies of
mailing list postings, and make the inverse of your request: That
people please never do that. They, too, are doomed to frustration.

(And there are also death and taxes.)


[1] Mail User Agent. A mail client.