[Mailman-Developers] Message threading - requesting some wisdom

[Andrew Stuart]

Hi folks

I assume a great deal of thought has gone into message threading and how it works. Is there anyone willing to share the basics with me - specifically as it relates to Mailman and related projects?

There is of course plenty of information on google which I am researching including the seminal http://www.jwz.org/doc/threading.html but if there is anyone on the Mailman team willing to give me a Mailman oriented understanding that would be great. It appears to me there are a number of ways to implement threading, and how it is done is somewhat arbitrary.  For example, this description of Gmail threading http://xkahn.zoned.net/software/evolution/threads/ seems to suggest that Gmail includes arbitrary business rules for threading based on message content (i.e. subject prefix).

In particular I want to know the basics of message threading - i.e. 

** What data defines how emails are connected to one another?
** How is that connecting data organised (i.e. in a tree, a flat list, by date, whatever)?
** What happens when thread data is missing (i.e. a message in a thread is deleted)?
** Are there any algorithms/mechanisms/patterns that are effective for implementing threading?
** Any code in Mailman/Hyperkitty/elsewhere that is particularly good to study?
** Anything else I should know?

I’m wanting to find the most simple and effective way to deal with threading which of course has the potential to be complex if I get it wrong.

thanks!

as