There are many e-mail lists, each devoted to some subject. I am thinking here mainly about lists where the contributors are among the recipients. There are several programs, list servers here, that run on some computer to support one or several such lists. There is typically a mail address, mail to which is broadcast to the recipients. This address is especially strong spam bait. Some list servers reject mail except from members. Some list servers present historical messages to web browsers, cross indexing the messages several ways. These web sites provide access the messages which in turn provide the e-mail addresses of the list members. These too constitute a target for spam.
Here is a scheme to launch DSR and ameliorate these mail list spam problems at once. The list server would encode the e-mail address of list members as they appeared in the relayed e-mail and also in the messages delivered via http to browsers. The server would admit and redistribute mail not conditioned on membership but upon payment.
This scheme might engender fears that pseudonymous remailers do. I am sympathetic with those but the spam problem can be easily solved with much less protection. I have seen automatic remailer software perform a simple Turing test to submitters of e-mail for the list. I think that this game goes to the tester but I have not given it much thought.