Yes, but you don't have to set p=reject to know how much mail you would
loose. That's what p=none monitoring mode is for.
And if you see that you will loose many mails from mailing lists, it is
not wise to change your policy to p=reject without fixing those problems
first.
It's not only mailing lists. Many website contact forms set the "From:"
address to be the address of the site visitor who filled in the form. If
they have AOL or Yahoo! addresses then the resulting email messages from
the web server will not be accepted by any compliant DMARC-checking mail
service (AOL, Yahoo!, and more. Currently Google accepts the mail but
marks it as coming from a suspicious source, contrary to AOL and Yahoo!'s
DMARC policies). The fix is to use the "Reply-to:" header instead, but
there are an awful lot of website forms out there that need fixing!
AFAIK even Google doesn't reject p=reject any longer. Instead they move
those mails into the Spam folder now.
I've seen them in the normal Inbox, but with a highlight saying that
they're from a suspicious source. Seems to be a sensible work-around to
the sudden p=reject problem that's now blighting website forms and mailing
lists all around the world!
Anthony
--
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Tel. 01903 867 810
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