We are now rejecting any incoming emails that fail dmarc for domains that have a p=reject policy. Because if we forward such emails through mailinglists they will cause bounces for some subscribers (eventually causing those subscribers to be unsubscribed).
https://inbox.sourceware.org/gcc-patches/e137cda184f7c54a91bb3966c1d067c92095eda6.camel@klomp.org