Message threading: reply message and In-Reply-To/References

[Francesco Ariis]

Hello Kevin,

Il 23 settembre 2020 alle 13:52 Kevin Shell ha scritto:
> In mail/news discussion,
> some reply messages have no In-Reply-To/References headers,
> what cause reply messages don't have In-Reply-To/References headers?

A possible explanation: the sender clicked «New message» and copy/pasted
the Subject instead of clicking «Reply».

> What message these reply messages
> linked to with regard to mutt message threading?

By default mutt checks In-Reply-To/References to group threads; *also*,
messages with the same Subject are grouped together in «pseudo threads»
(reference [1]).
Does this answer your questions?
—F

[1] http://www.mutt.org/doc/manual/#strict-threads