Reply-to-List, or Reply-to-All?
There is an open question about the best "netiquette" to use when replying
to mailing list messages — should you use "Reply to All" and include
the original sender of the message and all other recipients well as the list,
or should you use "Reply to List" and send your message only to the
Note that this is not the same topic as discussed in Chip Rosenthal's
Considerered Harmful" essay. That essay is about what the list
should do, while this page talks about your choices as the user who
is replying to the mail.
Firstly, it's important to understand how mailing list
software behaves. One of the most commonly used mailing list
managers is GNU
By default, Mailman will not send you a copy of
a list email if it sees that your address is already listed in the
To: or Cc: headers of the email. This can be
changed by logging into the list web site and changing the
Different people have different preferences, use different
software, and have different ways of processing their incoming
mail. For example:
Each of these people may have different preferences — it's hard
to know what to do for the best, and whether to include them in Cc
or not when you reply to their messages.
- John doesn't do any filtering — he isn't subscribed to many
mailing lists, so hasn't bothered to work out how to do it. The
default behaviour of Mailman means that if you Cc him on
a message which is also sent to a list he's on, he'll just get one
copy of it in his INBOX.
- Susan also doesn't do any filtering; she is subscribed to
the daily list digest to keep the amount of mail traffic down.
- Pete filters mailing list messages into separate folders, and
and has also kept the default "no duplicates" list
configuration. His filters match the List-Id: header
of an incoming message to determine whether it came from the
list. So if you send a message to both Pete and the list, he will
receive that message in his INBOX rather than the list
- James's set up is like Pete's, but his filters are slightly
different. His filters just trigger on the list address being in
the To: or Cc: headers. So if you Cc him
on a message to the list, it will land in his list folder not his
- Fred filters all incoming messages into separate folders according
to the list it comes from, and has told the list software that he
does want to receive the so-called "duplicates". If you
send a message which is cross-posted to two lists that he's
subscribed to, and Cc him directly because you know he has a
personal interest and you don't know that he's subscribed (or
suspect he might not be looking in those folders very often),
then he will have separate copies in each list folder, in addition
to the copy in his INBOX that he sees immediately.
- Claire is not subscribed to the list at all. She's been added to
Cc because she has an interest in this particular
discussion, and can offer expert advice even though she's not
usually involved with this project at all.
- Karl is not subscribed to the same list as you; he's subscribed to
a different mailing list. If you are participating in a discussion
which crosses project boundaries and is cross-posted to more than
one list, he will only see messages which are posted to
the list he's subscribed to.
Obviously if they have told you their preference, then that's not
so hard — just do as they ask. But most of the time you don't know;
you have to guess. And when we're working on mail software, we have to set
the default behaviour for a non-private reply. That's what prompted me to
write this page.
Pros and Cons
Let's look at what happens when you reply in each of the possible ways.
Firstly, if you choose 'Reply to List'...
Next, let's look at what happens if you choose 'Reply to All'...
- Claire is cut out of the discussion entirely.
- Susan doesn't get to see the message until the next digest is sent.
Which is usually OK as that's what she signed up for, but if she has
actively participated in the thread then she's now not going to see
your response until much later when the discussion has already moved
- Karl, and the entire mailing list that he's on, are also cut out of
- Fred is unhappy because although you're replying to a thread
he's actively involved in, and you may even be responding directly
to something he's said, you didn't do him the courtesy of a
direct Cc so it doesn't land in his INBOX. So he doesn't
see it immediately, and like Susan he might not actually spot it in
the list folder until much later when the discussion has moved on.
- John is happy. The message lands in his INBOX.
- James is happy. His filters put the message in his list folder.
- Pete is happy, because his filters will put the message
into his list folder where he wants it.
- Claire is happy. She was explicitly added to Cc because
her input is valued, and she continues to be part of the discussion.
- Susan is happy. Where she has actively participated in a thread, she
is included in that discussion in real time.
- Karl is happy. He may or may not be following the the list that he's
on at this precise moment in time, but the full discussion is there
in his list folder and doesn't disappear off into different forks in
- Fred is happy. The messages are in the correct list folder(s)
for posterity, and there's a copy in his INBOX which he'll see
and can respond to immediately.
- John and James are happy. The result is the same for them either way.
- Pete is unhappy, because he wants the message to go into the
list folder but it lands in his INBOX. He's also unhappy because
it doesn't have the List-Post: header which lets him
choose the "Reply to List" action on it.
You may not have spent too much time thinking about the different ways
that people handle email; hopefully the above has given you some pointers.
Now it's time for you to make your own decision — if you don't know
what the sender prefers, which one do you guess?
The corollary to the same question is: If you're working on a mail program,
what should you make the default behaviour, if the user doesn't
express a preference?
I've tried to stick to the facts so far and not offer my opinion. If
you don't want to know what I think, you can look away now...
To me, the answer seems obvious when you look at the failure modes:
Let's take a look at some of the details...
- If you "Reply to All" then some people may have configured their
filters to put the message in the wrong place. Or if it's a list
which doesn't automatically avoid the "duplicates" like Mailman
does, they might get a second copy of the message. Neither of these
are really the end of the world.
- If you "Reply to List" then some people could be cut out of the
discussion completely, and for a cross-posted discussion
you risk splitting the thread into separate discussions on the
Note that even if people are sent multiple copies of a message via
a substandard list manager which doesn't allow them to filter
duplicates, often they won't see them anyway because many mail stores
automatically eliminate messages with the same Message-Id
header, since that's supposed to be unique. (This isn't a stunningly
good idea, and Fred gets really unhappy if forced to use such a system,
but it is distressingly common).
Missing List-* headers
Pete was also unhappy that he couldn't use "Reply to List" on the
message which he received directly, because it doesn't have the list
headers. But we've just established that that's a benefit for
everybody else since he shouldn't be doing that anyway!
However, it does also mean that for such messages you don't get to
use the automated features like being able to unsubscribe using the
details in the List-Unsubscribe: header, and other such
things. Did you even know that was possible? When compared with the
possibility of cutting people out of the discussion, I think we can
agree that this is probably worth it. It's not as if it's hard to just
click on a different thread in the list to get those headers. So you're
actively participating in every thread in the list and it's hard
to find a message with the list headers? Tell me... why did you want to
unsubscribe, again? :)
Pete might not like being told that his filters are wrong. He might say
that filtering on To: and Cc: headers like James
does has false positives, and files messages into a list folder when
they didn't really come via the list. Pete is theoretically
correct to a certain degree, but filtering on the List-Id:
header also has false positives in some circumstances. The
best way to filter list traffic is actually on the Return-Path.
When this is pointed out, Pete will usually shrug his shoulders and
say that those circumstances don't happen very often and using
the List-Id: works well enough for him. That is probably
the point at which we might suggest to him that, while James's
method also has theoretical false positives, those are
actually making it do the right thing for him most of the time
— so Pete is probably better off using it.
I said "most of the time"... Pete might have a valid concern
that if a message is sent to more than one mailing list that he's
on, his filters might put it in the wrong place if he only filters
on the contents of the To: and
We should stop here and think for a second. What happens if we
pander to Pete's demands that we all use "Reply to List"? That's
right — we end up continuing the thread only on one of
the mailing lists, fairly much randomly chosen from Pete's point of
view, so he still gets the messages only in one of the
folders! It's just that everyone else is inconvenienced, some
in much greater ways, too!
But let's tell Pete how to fix it anyway. The best option, if you
really want this setup for your email, is a combination of filters
in two passes. First, do the "proper" filtering on
the Return-Path of each list, so that any message which
actually does arrive via a list is reliably filed into the
appropriate folder for that list. And then, if you really don't
want list conversations landing in your INBOX even after you've
actively participated in them, your filters can
also match on the To: and Cc: headers and filter
matching mails into the appropriate list folders.
But maybe it's not worth bothering with that second pass. It's not
like it's hard to move messages from your INBOX to a list folder if
you want that to happen. And you might get used to the fact that
when people are replying to your messages in a thread, you get to
see their response and respond to it immediately rather
than later on.
So there it is. Unless you know that the other people
involved in the discussion are like Pete (and either can't or won't
fix their own filters) — or that the list doesn't eliminate
"duplicates" and they object to them —
then you should always play it safe and use "Reply to All".
Deliberately replying only to one list and cutting others out of the
discussion is considered to be extremely rude by some
people. When they eventually find out.
Public vs. Private replies
So far, I've only spoken about the case where you know you want to
reply in public. When we're thinking about what mail software should do,
and what the default behaviour should be, we also have to consider the
question of "public or private?".
This one takes even less thought, and again the decision can be
based entirely on the failure modes:
So although people have occasionally asked for the default 'Reply' button and
the associated 'Reply to Sender' menu option to actually
reply to the list for list messages, that seems like a really bad idea
— and most of the time they realise this when it's pointed out to them.
- If you send a private reply when the user expected it to be public,
that is easy to fix — just forward or resend the message to
the correct place.
- If you send a public reply when the user expected it to be private,
the effects of that can be catastrophic — the public
message can never be retracted, and could be extremely damaging.
Any decent mail program will have separate options for a
private reply, vs. a more public reply — and the private reply option
should never trick you into replying back to the list.
For mailing list administrators, this is probably a reasonable time to refer back to the Reply-To-Harmful
essay that I mentioned in the second paragraph. Setting a Reply-To:
address to point back to the list is doing the wrong thing in
both ways. It's hijacking my private "Reply" button and
making it give a public reply, when I already had a button
that I could use if I wanted to make a public reply. And it's even giving the
wrong type of public reply — it's replying only to the list,
instead of to all the correspondents.
Please, never set a mailing list to have a Reply-To: header
point back to the list. That's like sending me a virus which infects my mail
program and hacks it so that it replies in public when I specifically pressed
the button which should give me a private reply. If I wanted to send
a public reply, the button for that is right next to the one I pressed!
If I'd wanted that, I would have pressed it.
Thankfully, I now have this to save me:
This is what we currently have in Evolution: a private Reply button, and
a 'Group Reply' button which gives you a dropdown choice of Reply-to-All vs.
You don't have to use the drop-down menu, of course — if you
just click 'Group Reply', it'll do the sane default which is Reply-to-All.
You can go into the preferences and change the default to be
Reply-to-List. Please don't, though.