As I've pointed out, a substantal amount of the unsolicited bulk
mail in my traps has headers just like mail from other "lists"
including this one.
Indeed, mailing lists run by idiots are a major source of spam. I've
lost count of the number of times I've been subscribed to a mailing
list without asking, often a mailing list I've never even heard of. I
get subscribed to lists that anyone who knows me would *instantly* know
I would never be interested in. (Most recent example: Christian
bookstore.)