Comment 9 for bug 418728

I agree that "Some or all..." is pretty awkward. I like Mark's suggestion in comment #7, but here's another option (albeit more weasel-y):

"Your message has been rejected, probably because you are not subscribed to the mailing list and the list's policy is to prohibit non-members from posting to it. If you think that your messages are being rejected in error, contact the maling list owner at %(listowner)s"