Warning: GeekFactor 7++
As I started evaluating forum software for the RETS.org user community, I ran across the need to export the old mailing list archives. The export was easy, as the entire history is still stored in an mbox flat file - so in essence getting the mail was already done.
I ran into the issue that keeping the email in a threaded state was going to need a nice little algorithm. Some Googling led me to an Jamie Zainski’s Threading which outlines the basic principles, all pertaining to interpreting the Email Header:
