[Mailman-Users] Yahoo Groups' From munging and X-Original-From

[Mark Sapiro]

On 05/25/2014 11:31 AM, Mark Rousell wrote:
> 
> Whilst mail client recognition of the X-Original-From header would alter
> what users see (which is in fact a key goal in this context, not a bug),
> DMARC would nevertheless still be effective in terms of its own design
> goals in that mail servers could still adhere to DMARC and reject or
> spamfilter non-compliant messages.


Until spammers figure out they can send mail

From: spammer at evildomain.com
X-Original-From: whatever at yahoo.com

DMARC doesn't stop it because evildomain.com doesn't publish a DMARC
policy, and the 'evolved' MUAs display the message as if it's from
whatever at yahoo.com, just what DMARC is intended to stop.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan