Legally binding, maybe But enforcable, hardly. Had the individual mailed you
directly and you published it to the web, then you would have been violating
the original intent of the sender, to establish a protected conversation
between the two of you (or, from the company's perspective, to share
privileged information with you, which you then made public).
Well, it's just weird. What if said person is engaging in harassment? Is it then illegal to go about spam if they include the little disclaimer? It doesn't make sense to me :P but oh well.
However, as the OP posted his message to the mailing list which is of course
archived, republished as digests, and generally available from the website.
So there was no intent on his/their part to discretely share information with
one or a few individuals.
Look at the guy that just got busted for releasing early information on some
apple product (the ipod mini, I think?) There's an example of what can
happen if you share info that is given to you by a corporate entity and you
go spreading it around.
That's a different case. IIRC the guy who leaked the info on the iPod shuffle/Mac mini broke an NDA he signed with Apple - which is then perfectly legal. Trade secrets and the like, I suppose.
But once the individual/company make it public (ala posting a message like
that to the list), it no longer carries privilege with it, unless of course
it contained information that you used in some way to develop a
