On May 12, 2014, at 1:38 PM, S Moonesamy <[email protected]> wrote:

> Hi Doug,
> At 12:16 12-05-2014, Douglas Otis wrote:
>> be compromised.  A better approach would not use DMARC, but would federate 
>> third-party services they can see their customers employ.  The federation of 
>> email, much like that of XMPP, would be an effective means to exclude bad 
>> actors without breaking mailing-list and other third-party email services.  
>> As it is now, it seems Yahoo only protects their own
> 
> Is federation effective in excluding bad stuff?  Bad stuff also occurs in 
> closed systems (see 
> https://support.twitter.com/groups/56-policies-violations/topics/238-report-a-violation/articles/64986-reporting-spam-on-twitter
>  ).  XMPP has been mentioned previously.  There wasn't any information 
> provided to assess whether it does exclude bad stuff.

Dear SM,

The goal of federated services is to prevent inclusion of unknown servers.  It 
does not in itself exclude bad stuff.  When bad stuff is noted, federation 
enables blocking future exchanges. Direct tweets are possible, although 
messaging constrained to 140 characters is difficult to take seriously since it 
is nearly impossible to know whether a tweet is being auto-generated.  Much of 
it is.  The way this would relate to DMARC is in the handling of non-aligned 
messages. When sources are identified, and feedback is generated for all known 
exceptions, it should not be difficult to then invert "block" logic into 
"accept" logic. 

Imagine your domain supporting millions of users had their accounts exposed 
along with their address-books.  This can easily get ugly in respect to the 
harm this would allow.  Yahoo likely considered DMARC the closest approximation 
of server federation that could be enabled.  After all, there are no other 
email policy layers reliably acted upon.   What is missing is a minor amount of 
feedback needed to communicate what the Author-Domain knows to be legitimate 
sources.  Doing so should represent a negligible amount of effort. 

I supported a system that reported on _all_ identified bad IPv4 addresses.  To 
do this, it required careful exclusion of those randomly assigned addresses.  
We would then apply about 15 million updates every 5 minutes for the entire 
IPv4 address space orchestrated by two redundant servers.  This information 
then supported several very large ISPs.  The larger ISPs wanted to do zone 
transfers, but a DMARC exception rate for an Author Domain will be several 
orders of magnitude lower in scale. I'll admit this was all done using C code 
that avoided SQL or Hadoop.  Judy is your friend. :^).

Regards,
Douglas Otis

  


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