autoresponding to Yahoo DMARC breakage

John R. Levine johnl at
Thu Apr 10 01:54:21 UTC 2014

> On Wed, Apr 9, 2014 at 6:11 PM,  <bmanning at> wrote:
>>         and just how is an algorithm supposed to detect that
>>         <jeff-kell at> is a single human and not a list?
> If the autoresponder is sane, it looks for:
> List-Id: North American Network Operators Group <>

Yes, there are a lot of headers that give you a hint that a message is 
from a list.  But the heuristic to look for the recipient's address on the 
To: line works so well, along with a little rate limiting, that you don't 
really need anything else.

John Levine, johnl at, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail.
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