Reply-To header

Mike Meyer mwm at
Mon Oct 3 22:50:08 CEST 2005

Peter Decker <pydecker at> writes:
> Setting the default Reply-To: to the list means that 'Reply' sends
> just to the list (the desired behavior most of the time), and 'Reply
> to all' sends 2 copies.

No, it sends one copy to the list, and one copy to the original
author. This is the behavior you want. The author may not be
subscribed to the list. Such people are most in need of help, and you
want the default to be that they get help.

There are a number of alternatives for users on the list to avoid
getting duplicates. Many lists can be configured to check the headers
for other recipients, and to remove them from the list for that
message. Many mail readers have functionality to detect and eliminate
duplicates - even MS LookOut has that! Personally, I wrote a qmail
dot-command to do it long ago. I can make my dot-commands available if
anyone wants them. There's also a mail header that's been around for
years that tells conforming agents to supress the copy to the
author. Some mail readers honor it, others don't.

> I'm on several other lists, some of which default replies to the list,
> and others which default to the sender. I've *never* seen threads like
> this on the former, while such threads appear like clockwork on the
> latter. Draw your own conclusion.

I see the threads you don't see. Usually started by someone accidently
sending a reply that was very much intended to be private to a public
list. This should be compared to the badness of hitting the wrong
reply when the list is configured properly: only one person gets a
copy. That's easily fixed by asking them to forward it to the list, or
simply reposting your message, with little or no harm done.

My conclusion is that people used to the correct behavior have given
up on fixing the internet, and use tools that fix the part of it they
can see. When I notice that a list is broken (RFC 2822 says that
reply-to is for the *author* of the message; anyone else setting it is
doing so in violation of the RFC, and hence broken, no matter how
useful it may be), I tell my mailer to ignore reply-to on mail from
that list. Similarly, I no longer try and explain to people how long
lines violate RFCs and are a pain to read in well-behave mail readers,
or why mail readers that wrap text/plain content are broken.
Likewise, I restrict my comments on top posting to noting that I've
fixed it (or given up on fixing it and deleted the text as useless)
when I follow up to such things. Asking people to change their ways
because it's better for others is a waste of time - most of the users
on the internet these days don't give shit.

>> Not that it matters that much to me, since I read practically all
>> mailing lists via That turns the lists into newsgroups, where
>> the reply button (follow-up, more accurately) does send the reply to the
>> newsgroup.
> So the answer is to not use the email interface, since the newsgroup
> interface actually gets it right!  :)

Newsreaders only gets it right if it sends copies to posters who
aren't subscribed.

Mike Meyer <mwm at>
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.

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