On 28 Jan 2019, at 3:35, Benny Kjær Nielsen wrote: [...]
I'm now at the point where I would automatically become suspicious if anyone (any webpage) seems to claim to fully understand the consequences of any kind of setup/setting related to this :-)
There are definitely some people (maybe dozens) with very deep understandings of DMARC and the consequences of all of its options, but they know better than to think there's a universal right way to deploy it trhat can be boiled down to a web page. I'm not one of those people but I know a few of them, and none are fond of general p=reject use, especially for domains used to provide mass-market retail/free mailboxes. Everyone who participated significantly in the DMARC definition process knew that all existing discussion group mailing lists operating across independent domains would be damaged by unwise use of p=reject. I'm pretty sure that some people see that as a feature, either because traditional mailing list behavior is inherently problematic and needs an incentive to change OR because they see an opportunity to advantage their own captive discussion groups. It's not accidental that the first significant mailbox provider to use p=reject was Yahoo.
The only real fix for mailing lists is to munge From headers, at least for list members who have p=reject domains. Disabling bounce processing is an unsustainable option and banning users in p=reject domains is impractical.
-- Bill Cole b...@scconsult.com or billc...@apache.org (AKA @grumpybozo and many *@billmail.scconsult.com addresses) Available For Hire: https://linkedin.com/in/billcole _______________________________________________ mailmate mailing list mailmate@lists.freron.com https://lists.freron.com/listinfo/mailmate
