Everybody wins!

There was a recent question on a mailing list during a discussion of spam and delivery problems. A number of folks who work in delivery were discussing how a bad address got on a list. Someone who works on the spam blocking end of things asked why do you care how a bad address got onto a mailing list?
For recipients, they usually don’t care. They just want the unsolicited mail to stop. It’s a position I have no problem with; I want the unsolicited mail to stop, too. But understanding why a particular sender is sending mail to addresses that never asked for it can be an important step in making it stop. Not by the receivers and the spam filters, they’ll just block the bad sender and move on. Or if they’re an ISP or ESP they’ll just throw the sender off for AUP violations and let the sender be somebody else’s problem.
In the broader context, though, this only changes the source of the spam. It doesn’t help the victim; the bad sender can always find another host and they will continue to mail people who never asked for that mail. And, in fairness to these senders, often they are mailing lists of mixed sources. Some of the addresses didn’t opt-in, and don’t want the mail, but a lot of addresses on their list did opt-in and do want their mail. Fixing their problem means they can mail people who want their mail. The sender is happy, the recipients are happy and the receivers are happy; everybody wins!
Everybody winning is something I can get fully behind.