[Mailman-Users] Emails from yahoo members, are getting rejected by yahoo, "Service Unavailable".

[Jim Popovitch]

On Sun, Apr 13, 2014 at 4:54 PM, Joseph Brennan <brennan at columbia.edu> wrote:
>
> Jim Popovitch <jimpop at gmail.com> wrote:
>
>> DMARC works off of SPF as well.
>
>
> Not really.

DMARC checks alignment of *both* DKIM and SPF, if either is broken DMARC fails.

> SPF does not check the "From:" header line, and that's where the
> troubles begin with DMARC.

SPF checks sending IPs (of which your IPs won't match Yahoo's, thus
breaking DMARC)

Either an SPF failure or a DKIM failure will cause a DMARC rejection
if p=reject.

-Jim P.