Thank you for the report. I've never seen this (or maybe just never noticed it), but I accept that it happens. I suspect at some point Mailman may have received a message From: user@AOL.com and looked up _dmarc.AOL.com in DNS and a result is cached. This message may be properly mitigated because there was no case mismatch, but a subsequent message From: user@aol.com gets the cached result and there is a case mismatch. However, when I try `dig _dmarc.aol.com TXT` and `dig _dmarc.AOL.com TXT` multiple times in succession the case in the answer always matches the question, so that may not be the reason. ** Changed in: mailman Importance: Undecided => Low ** Changed in: mailman Status: New => Triaged ** Changed in: mailman Milestone: None => 2.1.34 ** Changed in: mailman Assignee: (unassigned) => Mark Sapiro (msapiro) -- You received this bug notification because you are a member of Mailman Coders, which is subscribed to GNU Mailman. https://bugs.launchpad.net/bugs/1881035 Title: DMARC mitigation fails if TXT record name contains uppercase To manage notifications about this bug go to: https://bugs.launchpad.net/mailman/+bug/1881035/+subscriptions