Judy,
Could you look into tweaking the settings for The Parlor's mailing list "mirror"? There are two features I'd like adjusted:
1. There are several broken threads for users of TAPCIS, which does not track the Message-ID and References headers which are used to properly thread messages posted using more modern clients. The documentation page suggests that there is an "Optional setting to thread by subject for mailing lists that strip references header."
Could you try to turn on "thread by subject"?
2. Messages posted via email contain a Yahoo Groups footer:
The documentation suggests that you can "Strip footer by setting for incoming messages. Strips out repeated message footers." Could you try to strip those footers, please?