[Mailman-Users] Reply-to options not working

Grant Taylor gtaylor at tnetconsulting.net
Wed Jan 24 13:02:48 EST 2018

On 01/24/2018 01:50 AM, Stephen J. Turnbull wrote:
> I'd appreciate if those who have strong opinions on this would take a 
> look at the analysis below and tell me if I'm missing something.  If not, 
> maybe I'll write up a BCP (non-standards-track RFC[1]) so it's on record.

See my comments inline below.

> This proposal actually has a history going back to about 2005.  I didn't 
> do anything about it because I got a lot of pushback from MUA writers, 
> and writing RFCs is worse than writing PEPs (Pythonistas are either sane 
> or go away soon, not so for IETF mailing lists .  But if its still an 
> issue maybe it's worth the effort.
> I think there's an obvious algorithm for "smart single reply":

I doubt that's the case.

> 1.  If there is a Reply-To, address the message to Reply-To.

Baring other influences, this is where the author or the message sender 
(if it's someone other than the author) wants replies to go to.

> 2.  Else if there is a List-Post, address the message to List-Post.

I don't think that it's appropriate to always prefer the List-Post over 
the From ~> Reply-To.

MUAs (are starting to) have separate functions for reply to From / 
Reply-To vs reply to list.

I can see a case for a broadcast mailing list that's open for all 
members to post to where neither From nor Reply-To munging takes place. 
The author can send from one address (From) and want replies to go 
elsewhere (Reply-To) while the MLM adds a List-Post header to comply 
with other standards.  I feel like a reply to such a message should go 
to the Reply-To (as set by the author) and not the List-Post as set by 
the MLM.

Reply-List in such a case is a distinctly different operation.

I can also see a case where a message author might choose to 
(dynamically) set the Reply-To to something like "Reply-To:  Please 
reply to the Mailman-Users mailing list. <mailman-users at python.org>"

> 3.  Else address the message to From.  (If there's no From, the message 
> violates the most basic RFCs so all bets are off.)


Sounds like the classic case of "undefined behavior" to me.

> Assuming that no lists munge Reply-To, I think you'll agree that this 
> is what you want 90% of the time (conservative estimate).  There are 
> some issues with this algorithm in practice:

I disagree for a number of reasons.  Some of which are outlined above.

> 1.  Some lists should not encourage reply-to-list (eg, for privacy 
> reasons).  This can be worked around by omitting List-Post, or solved 
> by additional protocol so that the list sets a header field saying 
> "don't automatically reply here just because there's a List-Post. 
> Given how conservative MUA writers are, I'd say "KISS" for these, 
> and make users cut-n-paste.  Most of the time a reply-to-list here is 
> probably thread hijacking anyway.

I see an opportunity for a "List-Reply-To" header that could indicate if 
/replies/ should go to the list (List-Post) or the author 
(Reply-To|From).  I suppose that it could also be possible to specify an 
alternate address for replies to go to, i.e. for thread tracking or 
something like that.

This would still leave us in the situation where MUAs need to 
differentiate between a generic Reply and a Reply-to-List behavior. 
Plus the associated action for the reply keyboard sequence.

I feel like this is /mostly/ a user education issue.  There may be some 
room for UI / UX improvement.  Ultimately it's up to the MTA to do what 
the user wans done.  Consider the following:

From: Author <author at author.example>
To: List <list at list.example>
Reply-To: Author <author+list at author.example>
List-Post: List <list at list.example>

Where should replies to the author go to?  Where should replies to the 
list go to?  Where should the (undefined) "reply" go to?

I don't think that it's likely for the MTA to automagically know what 
needs to be done.

> 2.  Some users will want to override the algorithm and reply specifically 
> to list or author.  MUAs should provide buttons or menu items for these 
> infrequently used options.

I think it is wrong for us to ascribe frequency of use for other users. 
Just because I do something some way does not mean that others do so 
with the same frequency, or even the same thing.

I personally use Reply List more than I use Reply (Author [From|Reply-To]).

> 3.  Your favorite list munges Reply-To.  Nothing changes here, people are 
> still going to be embarrassed by sending remarks intended to be private 
> to a broad audience, and in some configurations of Mailman the original 
> Reply-To or the From will get dupes.  At least you can override with a 
> reply-to-author function.

I feel like this is a user education issue.  Sadly, pain of 
embarrassment is a good teacher.

> I don't understand what Thunderbird thought they were doing. <shrug/>

I think they were trying to apply a technological solution to what I 
believe is fundamentally a user education issue.

Grant. . . .
unix || die

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