On Tue, Mar 28, 2017 at 06:35:55PM +0100, Peter Maydell wrote: > 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
Option 3 sounds good given that Option 2 is unlikely to be reliable (e.g. DKIM-signing). > (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
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