On Mon 2019-11-11 10:26:18 -0500, Daniel Kahn Gillmor wrote:
>  - What is the specific use case for this? For example, can you identify
>    situations where different headers need to be emitted by different
>    users?  Even one motivating example would help others on this list
>    understand why they might want to care :)

ah, sorry, i've just read id:20191109221358.4349-1-johan.parin@gmail.com
and its associated messages, so i can see that some of the questions i'm
asking are already under discussion.

I see that you just want user-agent and x-mailer for your own purposes.

Maybe it would be worthwhile to propose that narrow, limited change as a
simple patch, without configurability and see what it looks like?  I
would personally be more likely to advocate for merging a patch that
meets the specific needs of a notmuch user, and increase the
configurability surface of notmuch.

If processing a couple of extra headers on a long thread is too
expensive for some consumer, i'd suggest that is an optimization for the
consumer to tackle.

    --dkg