| Unsolicited bulk e-mail (spam) threatens e-mail's effectiveness for communication. Existing techniques that aim to reduce or prevent it decrease e-mail's reliability or place unnecessary restrictions on e-mail's use. This thesis describes a system, the Spam Free e-Mail (SFM) service, that effectively eliminates spam without such drawbacks.; SFM combines challenge/response techniques with mail channels, allowing it to eliminate spam and support solicited bulk e-mail. Its subscribers initially create one or more e-mail addresses that they can openly share and publish. Messages sent to them never reach the subscriber; instead, they solicit an automatic response from the system. The response communicates a new e-mail address unique to the sender and prompts the sender to resend the original message to it. To solicit a bulk mailing, subscribers can manually create one of these alternative addresses unique to the bulk mailer. |
