On Mon, 13 Mar 2017, Phillip Hallam-Baker wrote:
Perhaps we should just recognize the fact that SMTP does not really
support mailing lists, ...
These complaints had nothing to do with lists or DMARC. They were about
sending ordinary unauthenticated mail over IPv6. If they wanted to fix
that problem, they could do so in 10 minutes by publishing an SPF record,
with no other changes to the way their mail works.
R's,
John