Hi; it's been pointed out to me that we have a problem with qemu-devel unsubscribing people because of DMARC. Specifically: * microsoft.com publishes a DMARC policy that has p=reject * some subscribers use mail systems that honour this and send bounces for non-verifying emails from those domains * the mailing list software (mailman) modifies emails that pass through it, among other things adding the "[qemu-devel]" subject tag, in a way that means that signatures no longer verify * bounces back to mailman as a result of mailing list postings from microsoft.com people can then cause people to be unintentionally unsubscribed
This is kind of painful. https://wiki.list.org/DEV/DMARC has the Mailman wiki information on the subject. In an ideal world nobody would use p=reject because it breaks mailing lists. In the actual world we have a few choices: (1) I could set dmarc_moderation_action=Reject * this means nobody can subscribe if they've set their dmarc policy to reject (the "if you don't believe in mailing lists we don't believe in you" policy). * there is a certain purity to this option, in that it is pushing the costs of this unhelpful mail config back on the organisations which have chosen it; on the other hand I'm reluctant to make life harder for people who are contributing to the project and who typically don't have much say over corporate email config. (2) I could reconfigure mailman to try to not rewrite anything that we think is likely to be signed (in particular not the body or the subject) * this means dropping the [qemu-devel] tag from the subject, which I'm a bit reluctant to do (it seems likely at least some readers are filtering on it, and personally I quite like it) * if anybody DKIM-signs the Sender: header we're stuck anyway (3) I could set dmarc_moderation_action to Munge From, which means that those senders who have a p=reject policy will get their mails rewritten to have a From="Whoever (via the list) <qemu-devel@...>" and their actual email in the Reply-to: * if anybody's mail client doesn't honour Reply-to: then what they think is a personal reply will go to the list by accident (4) I could do nothing, and hope that we don't get so many of these that they actually result in unsubscriptions * in any case emails won't end up going through to some recipients, so this isn't much of an option anyway (5) I could set the bounce processing config to be (much) less aggressive * this seems like a bad idea * in any case people whose systems honour DMARC still wouldn't get mails from the p=reject senders I don't really like any of these choices. For the moment I have picked option (3), but I'm open to argument that we should pick something else. thanks -- PMM
