There's an obvious solution to this problem which will satisfy
(almost) everyone.
Set up two lists, one with each behavior. Arrange for a single address
to mail postings, which get distributed to both lists. (It would be bad
to have two addresses, as inevitably someone would send the same postings
to both.)
Each individual subscriber can choose which header style he or she desires
by subscribing to the appropriate list.
This requires a bit more work (one time) on the part of the system
administrator (Jay). I'd be willing to help with that.
(This would be even easier with mailing list software that sent each message
separately per subscriber, as is done by Ezmlm. But I don't think Majordomo
works that way.)