Thoughts on spam
[Cross post of my comment in libertarianism.]
It is a mistake to ask the government to step in just because some people are too stupid to stop saying "If you'd like to waste my time with your solicitation, I'll pay for the shipping."
Opening port 25 and accepting SMTP traffic is an invitation for other people to send you email. If you've done this [or if an ISP has done this on behalf of you and their other customers], people have been invited to send SMTP traffic (email messages) to that port.
You [or your ISP] should feel free to reject unwanted messages, to reject messages from know abusers, to close the port and stop accepting messages, or to use a protocol that requires authentication before accepting data.
Everyone I know gets physical junk mail. The primary difference with email is that the costs for the sender are much lower and the recipient may pay some cost to receive email. Things don't have to be that way. A different system could be set up to shift the costs around and let friends through for free. Each recipient can tweak the current system a little bit so they reject unwanted messages. The fact that spam is thriving in a situation where people haven't taken these steps should not be surprising.
Some people say the sender is at fault for abusing the recipients email box, for "forcing" them to pay for unwanted messages. That is absurd. They are not required to have an email address. They are not required to ever give that email address to anyone at all. They are not required to keep the same email address. They are not required to read their email. Nothing prevents them from filtering their email....
Other people say the recipient is being a damn fool if the situation bothers them enough to complain and they haven't bothered to avoid being taken advantage of.
Nothing about this situation requires government intervention. Email is entirely consensual. People are only "abused" to the extent that they invite and tolerate that abuse. They can each stop the "abuse" any time they like.