On Wed, 17 Mar 2021 12:53:58 +0000 (GMT)
Jim Jackson <jj@???> wrote:

> for the record alpine is broken in that area. As far as I can make
> out it just uses the subject line to "thread" emails (modulo the
> various "re:"s etc)


It's a while ago that I used (al)pine (in fact, it was still pine back
then, IIRC in combination with fetchmail). Nevertheless, I'd bet that
you can make alpine sort threads by the "References" header. Just out
of curiosity, I did a quick websearch and found the following document:

http://www.chiark.greenend.org.uk/doc/alpine-doc/tech-notes/config.html#show-sort

libre Grüße,
Florian