K-9: Change reply behavior

[cketti]

Sometimes users seem to be surprised about the way K-9 Mail selects recipients when the "reply" action is used. I'm proposing to add more options with names that hopefully make it clearer which addresses will be selected as recipients.

Proposed behavior described via examples:

From: [email protected]
To: [email protected]

Displayed actions (in order):

• Reply ([email protected])

---

From: [email protected]
To: [email protected]

Displayed actions (in order):

• Reply ([email protected])
• Reply to all ([email protected], [email protected])

---

From: [email protected]
To: [email protected]
Reply-To: [email protected]

Displayed actions (in order):

• Reply ([email protected])
• Reply to all ([email protected], [email protected])

---

From: [email protected]
To: [email protected]
Reply-To: [email protected]

Displayed actions (in order):

• Reply ([email protected])
• Reply to all ([email protected], [email protected], [email protected])

---

From: [email protected]
To: [email protected]
List-Post: <mailto:[email protected]>

Displayed actions (in order):

• Reply to list ([email protected], [email protected])
• Reply ([email protected])

---

From: [email protected]
To: [email protected]
Reply-To: [email protected]
List-Post: <mailto:[email protected]>

Displayed actions (in order):

• Reply to list ([email protected], [email protected])
• Reply ([email protected])

---

From: [email protected]
To: [email protected]
Reply-To: [email protected]
List-Post: <mailto:[email protected]>

Displayed actions (in order):

• Reply to list ([email protected], [email protected])
• Reply ([email protected])
• Reply to all ([email protected], [email protected], [email protected])

---

From: [email protected]
To: [email protected]
Reply-To: [email protected]
List-Post: <mailto:[email protected]>

Displayed actions (in order):

• Reply to list ([email protected], [email protected])
• Reply ([email protected])

---

From: [email protected]
To: [email protected]
Reply-To: [email protected]
List-Post: <mailto:[email protected]>

Displayed actions (in order):

• Reply to list ([email protected], [email protected])
• Reply ([email protected])
• Reply to all ([email protected], [email protected], [email protected])

---

From: [email protected]
To: [email protected]
Reply-To: [email protected]
List-Post: <mailto:[email protected]>

Displayed actions (in order):

• Reply to list ([email protected], [email protected])
• Reply ([email protected])
• Reply to all ([email protected], [email protected], [email protected])

---

From: [email protected]
To: [email protected]
Reply-To: [email protected]
List-Post: <mailto:[email protected]>

Displayed actions (in order):

• Reply to list ([email protected], [email protected])
• Reply ([email protected])

- Reply to all ([email protected], [email protected], [email protected], [email protected])

Feedback is very welcome.

---

Update 1: Incorporated feedback from https://github.com/k9mail/k-9/issues/3738#issuecomment-440997017
Update 2: See https://github.com/k9mail/k-9/issues/3738#issuecomment-441495208

[Valodim]

Thanks for compiling this list, very helpful :+1:

I think it's customary for list replies to reply to both list and sender. It's rarely harmful at least, and removing recipients from the list is easier than adding more. That way we can get rid of an entire option, since "reply to list" and "reply to all" become the same for typical list messages.

Any thoughts on dropping the general "Reply" in favor of "Reply to sender" whenever it's ambiguous? While it's consistent to say "reply means reply to sender", at least for me that is rarely the "do what I mean" option I expect from a general "Reply" button.

[cketti]

I updated the examples based on @Valodim's feedback.

One thing I don't know how I feel about is the fact that this more or less ignores Reply-To when a List-Post header is present and it's different from the Reply-To address. Should we add a "reply to suggested" option? This could be useful if someone sends a message to lots of mailing lists but wants to direct replies to a particular list.

[wiktor-k]

One thing I don't know how I feel about is the fact that this more or less ignores Reply-To when a List-Post header is present and it's different from the Reply-To address.

There is one case that I think may be relevant here.

Some mailing lists add a Reply-To header and modify From (probably due to the fact that modifying the e-mail could trigger DMARC failure, and they add some ML boilerplate to the footer).

An example (anonymized):

Message-ID: <[email protected]>
List-Post: <mailto:[email protected]>
From: X via Gnupg-users <[email protected]>
Reply-To: X <[email protected]>
...

[Valodim]

What we need to work out is what "reply to sender" means for a list, and how it is affected by different constellations of List-Post, Reply-To and From. I wonder about this constellation:

From: [email protected]
To: [email protected]
Reply-To: [email protected]

Shouldn't "reply to sender" here reply to [email protected]? That's the purpose as written of Reply-To header at least:

If the "Reply-To" field exists, then the reply  should
           go to the addresses indicated in that field and not to
           the address(es) indicated in the "From" field.

This becomes more ambiguous with mailing lists, which might abuse "Reply-To" as "List-Post".

From: [email protected]
To: [email protected]
Reply-To: [email protected]
List-Post: <mailto:[email protected]>

In this case, "reply to sender" should obviously to go [email protected], however if Reply-To and List-Post weren't the same I would say "reply to sender" should go to what Reply-To says. This especially covers the case of DMARC-ified sender addresses where the mailing list takes responsibility for the message and puts itself as From.

[cketti]

My previous proposal used the Reply-To address for "Reply". But if we name the action "Reply to sender" I assume non-technical users would expect that the From address is used.

Maybe we shouldn't try to be smart with replies and just give Reply-To its own action. Then also display the Reply-To address in the message view header and let users figure out that there are more reply options when a Reply-To header is present.
The case where Reply-To and List-Post both contain the same address can be easily detected and we treat it like the case where Reply-To is not present.

[Valodim]

I assume non-technical users would expect that the From address is used.

I'm not so sure about that. Non-technical users have no concept of a "from" header, they just want the message to go to the sender. This also aligns with the RFCs. Do you have data to the contrary?

[cketti]

We display the information from the From header as sender of the message. How can non-technical users not be surprised if that information is not used when they click "reply to sender"? And we don't display the Reply-To information at all. So, really, they have no chance to figure out what's going on.

"Reply to sender" would also be the wrong name if it's used like this (message received via list2, but sender wants discussion to happen on list1):

From: [email protected]
To: [email protected], [email protected], [email protected]
Reply-To: [email protected]
List-Post: <mailto:[email protected]>

[gdt]

To me, the most important thing is that "Reply (implicitly being to the sender" and "Replay All (which could involve list-post)" must be separate and that when people execute the "reply to sender" action, the reply should not end up being posted anywhere. I think it's fine to show "reply" as "reply to sender" to help people who don't get that this is what reply has meant forever. I think it's also fine to make "reply-all" use list-post headers and send the message to the list only. Doing this right requires a combination of

• k-9 uses only From and Reply-To, following RFCs, when doing "reply"
• lists do not misuse reply-to
• lists do not misuse From, by rewriting it to be the list

The second and third points are difficult, particularly given yahoo/DMARC. The reply-to header is only supposed to be added by the originator, and should only me an address of the originator. It is abuse for the sender to decide for replies to go anywhere else. It is also abuse for mailinglists to set it. It's also even more abusive for lists to change the From to an address that goes to the lists, (instead of a per-member alias that just goes to that member, or declining to accept members whose MTAs reject list mail).

So I think what's needed in MUAs in general, is some way to detect misused From and Reply-To, perhaps by matching up list-post or list-id and values that correspond to those, and in that case, make reply grayed out with a popup that the is misconfigured (or softer if you are feeling charitable about this, which obviously I'm not) and refuse to perform the action because it can't be done.

The key property is that no one should ever click "reply" and have their response be public.

[cketti]

Dealing with mailing lists that rewrite From headers or "abuse" of Reply-To seems like a topic for another GitHub issue. Please feel free to create one with suggestions.

Given the reality that Reply-To is used differently than originally intended, I don't think we should call the action "reply to sender" if the Reply-To address is used.

My revised proposal:

• If Reply-To and List-Post are the same, ignore the Reply-To header for all following steps.
• If present (and not ignored) use the Reply-To value for the "reply" action (don't call it "reply to sender", because it might not be).
• Use List-Post value and the address that is used for "reply" for "reply to list".
• Use all addresses for "reply to all", i.e. also the From address even when Reply-To is present. Because it's easier to remove unwanted addresses than to manually copy & paste one that is missing.
• Display the Reply-To address when viewing the message. Hopefully this will help to understand why sometimes "reply" does unexpected things.

This can't guarantee that "reply" will never make the response public. But I currently don't see how that could be achieved.

[nomis]

I think it's customary for list replies to reply to both list and sender. It's rarely harmful at least, and removing recipients from the list is easier than adding more. That way we can get rid of an entire option, since "reply to list" and "reply to all" become the same for typical list messages.

Please don't do this, "reply to list" should be a separate option and only reply to the list. I'm fed up of people sending me duplicate messages to different folders by copying me in mailing list replies.

[neiljerram]

Is this change going to actually happen soon? After an accidental and semi-embarrassing reply-to-list today - again - I've ended up here, and it's clear that many k9 users have been burned by this, not just me.

Could we at least have an option - soon - to ignore List-Post?

(In my view List-Post should have nothing to do with replying. It tells you how to write a new message to the list.)

[Geobert]

Yes please, I messed up my first reply in my new job because of that x)

[sfrost]

To get back to the discussion, there's absolutely mailing lists which very intentionally do (and I happen to be involved in running this one...):

From: PG Bug reporting form [e-mail]
To: [email protected]
Cc: [email protected]
Reply-To: [email protected], [email protected]

Nearly every client out there correctly handles this (Thunderbird, by default, is broken but thankfully has an option to un-break it) and utilizes the Reply-To for replies, as one typically expects. I also agree with the comment above that List-Post header shouldn't be relevant for replies.

That k-9 mail users aren't having this 'just work' is rather annoying. Please fix.