[ietf-dkim] Change to Section 6

[Douglas Otis]

On Jan 19, 2007, at 1:35 PM, Paul Hoffman wrote:

> At 9:59 AM -0800 1/19/07, Douglas Otis wrote:
>> On Jan 19, 2007, at 3:57 AM, Stephen Farrell wrote:
>>> 6. Verifier Actions
>>> ...
>>> Since a signer MAY remove or revoke a public key at any time, it  
>>> is  recommended that verification occur in a timely manner. In  
>>> many  configurations, the most timely place is during acceptance  
>>> by the border MTA or shortly thereafter. [In particular,  
>>> deferring verification until the message is accessed by the end  
>>> user is discouraged.]
>>
>> This precaution should be removed!!
>
> I disagree with Doug and agree with the wording in the current  
> document.

Paul,

Would you explain the reasoning for discouraging verification at the  
MUA?

When annotations are applied by the MUA based upon email-addresses  
trusted by the recipient (which is how recipients might achieve look- 
alike spoofing protections at no cost), then verification should take  
place at the MUA and not at the MDA.  While DAC listed signing- 
domains might provide a category of annotation that can be applied at  
the MTA, there are many cases where third-party assurance is not  
required for protection to be realized.  Discouraging verification at  
the MUA seems aimed at only permitting third-party assurances as a  
means for annotating messages. : (

What prevents public keys from remaining available for a reasonable  
period to accommodate MUA use?  What annotation criteria can be  
safely applied at the MDA?  How can verification results be safely  
communicated to the MUA for email-address specific annotation?

-Doug