I can think of only one example of such mandates actually being enforced -
the fight against "open mail relays" a dozen years ago. The self-appointed
Internet police, or vigilantes, detected SMTP relays that could forward
spam, shamed them, and blacklisted them until their fixed their setup. The
relay operators could fix their operation, or face customer complaints that
their mail was being rejected. It was bitter, but there are very few open
mail relays left operating now, so in a sense we could say that vigilantism
did work. On the other hand, it is not like spam disappeared.
Actually, the biggest reason open relays went away is that popular
MTAs changed the default configuration to be closed. The various open
relay testers, one of which I used to run, were mostly used by system
managers to check that their config was really closed.
The various blacklists had some effect and certainly provoked loud
self-righteous complaints, but they've all gone away (except of course
for John Gilmore) since people realize the operational benefits of not
allowing criminals to use their systems to send spam.
I'd hate to think that the relative volume of spoofed packets would
have to approach the relative volume of spam to get people to do
something about it.
R's,
John