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

Mark Sapiro mark at msapiro.net
Mon Apr 14 16:27:17 CEST 2014

On 04/14/2014 06:46 AM, Joseph Brennan wrote:
> It finally occurred to me that this affects routine forwarding too. Even
> if you implement SRS on the envelope, the header From is left alone, as
> per RFC 5322.

Not necessarily. If the message is actually from Yahoo, it will be DKIM
signed with d=yahoo.com, and if the forward doesn't break that sig, the
message will pass DMARC.

> It also affects a message from any of our users who authenticates with
> our user and password but prefers to send with a yahoo.com From line.

Yes, This is exactly what DMARC is trying to prevent.

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

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