Quoting aaronco36 (aaronco36@SDF.ORG):
Am wondering what the TL;DR of all this is, i.e., the summarized outcome and current status of all Michael P's efforts here?
I think he means he successfully used balug-test as a test case (pun semi-intended) for import of mail to the mailing list's mbox and generation of the archive. This was to gain confidence that doing likewise to the main mailing lists has a good plan.
For balug-talk in particular (maybe some others), Michael has in mind to attempt to assemble a more-complete history, adding posting salvaged from other sources such as subscribers' saved mail, and merging that into the mailing list's mbox as a basis for running $MAILMAN_HOME/bin/arch to make a new pipermail archive. Seems worthwhile, but doubtless it'll take some time, and he might have to bodge headers on some of the saved mail to make it work. (You ask subscribers whether they have old postings in mbox format, and in my experience they send you the damnedest random formats, disregarding the qualifier about 'mbox' because they didn't understand it and weren't smart enough to ask. I experienced this when sf-lug mailing list subscribers supplied backfill material for that archive. A lot of what I got was not at all what I asked.)
Sufficent scripting-fu can, in my experience, reassemble an mbox that $MAILMAN_HOME/bin/arch will parse correctly. Just make sure that you keep a safety copy of the most recent mbox _verified_ to parse right, so you don't burn your bridges, only your spare time.
I believe backfilling the archives is the only task remaining. (Dreamhost "oops"-discarded quite a lot, over the years.)