I agree it's hypothetically possible, but have you ever seen an actual
need for this in practice, a list where the recipients filter out
messages that a more competently managed list would have rejected?
I've seen spam posted to mailing lists. Recently, I've seen lists targetted
in more intelligent ways by spammers. For example, by using sender
addresses in the domain of the list (quite a useful way of attacking
academic lists, which tend to have lots of local users, but some non-local).
I believe it. Are you saying the list managers make no effort to keep
the spam out of their lists? Remember that every change to list
software that might be useful to let recipients identify spam that
leaks through a list could be used to keep the spam from leaking in
the first place. Why go to extra effort to push the work out to the
subscribers?
Also, re your other discussion about list authentication, you're
right, we don't know what authentication lists do on their
contributors, but DKIM doesn't help there since DKIM most definitely
never says that the From: address is "real". If you want strong
sender authentication, we already have S/MIME, and I wouldn't be
surprised if there were list software that could use it.
R's,
John
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