On 13 Mar 2017, at 18:43, John R Levine <johnl@xxxxxxxxx> wrote: > > You can complain about how stupid they are or you can upgrade your mail system to use authentication methods that have been IETF standards for a decade and get your mail delivered. Your choice. The most likely outcome is that local admins will “upgrade" our mail system by turning off IPv6. (We have had IPv6 deployed for some 18 years now.) Grüße, Carsten