[dkim-dev] dkim and email list software - potential solution

[Hector Santos]

Douglas Otis wrote:

> On 9/30/09 12:46 AM, Daniel Black wrote:


>> odd - this is not mentioned in rfc5016
> 
> You need to talk to John Levine about the motivations for the
> "discardable" assertion.  This assertion was not part of the initial
> plan.  Providers may have wanted to avoid compliance issues with
> RFC5321 in some cases, since DKIM evaluation often occurs after message
> acceptance.  


ADSP-DISCARD allows you to throw away mail without creating 
backscatter (accepted mail non-delivery notifications).

If ADSP is evaluated at the SMTP DATA stage (before message 
acceptance), this could result in a negative reply code which will be 
a reject from the POV of the client and it can now initiate its own 
bounce notification or other action.

If the client is a MLS smtp outbound client, list recipients who had 
nothing to do the original message, could be at risk for lost of 
membership when their MDA continue to reject such ADSP failures.

This suggest that for dynamic SMTP servers with embedded filtering at 
the DATA stage, will probably need to mark the ADSP failure, accept 
the message and silently discard the message either at the QUIT or 
RSET stage.

This will help avoid the creation of ADSP based backscattering and 
negative recipient actions taken by mail list servers.

-- 
Sincerely

Hector Santos
http://www.santronics.com