In article <1ca714d0-da89-aa23-d247-4faa2133b...@msapiro.net> you write: >DMARC checks won't help prevent posts that spoof a member address unless >every list member's domain publishes a DMARC policy of quarantine or >reject, and even then it only checks the From: domain and not the domain >of other addresses Mailman might use to determine list membership. > >Further, a post with spoofed local part sent by someone in the same >domain might pass DMARC if sent via the domain's servers.
That's all true, and if you want bullet proof spoof resistance, you'd have to register PGP or S/MIME keys for the subscriber and require that she sign all her mail. On the other hand, a lot of domains do DKIM signing or publish SPF, and the vast majority of fake From: headers I see are from botnets, not malicious users down the hall from the victim. So if someone is experiencing a lot of botnet spoofage, a setting to say that a user's mail will be authenticated by SPF or DKIM from domain X would get you about 90% of the effect of S/MIME signing everything with 10% of the grief. R's, John ------------------------------------------------------ Mailman-Users mailing list Mailman-Users@python.org https://mail.python.org/mailman/listinfo/mailman-users Mailman FAQ: http://wiki.list.org/x/AgA3 Security Policy: http://wiki.list.org/x/QIA9 Searchable Archives: http://www.mail-archive.com/mailman-users%40python.org/ Unsubscribe: https://mail.python.org/mailman/options/mailman-users/archive%40jab.org
