I hope you're right, and encourage you to drive this point with the
ISPs. It would also be interesting to get some direct feedback from
them on this point- it would be useful to have some data. ISPs tend to
have concerns with abusive use of their email addresses just as many
other large brands do, so I would tend to expect them to push for at
least dkim=all publication. If it is in fact reasonable to expect that
ISPs will tend to stick to 'unknown', then the impact on these small
senders should be relatively minor.
Any ISP is going to have to weigh the security of their entire domain
against the convenience desired by a few users. Some will default to
the latter, some will choose the former. This is all still very new --
we won't see a standard practice emerge for a few years, at best.
ESPs should think of this as an upsell opportunity, and encourage your
users to get their own domains so they can (pay you to) set their own
policies!
--
J.D. Falk
Receiver Products
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