Is it prudent for domainkeys to attempt making assurances for the local-
 part of the mailbox address?  Not accommodating this local-part assurance
 (via individual keys), would acknowledge domainkey's relative weakness in
 terms of its ability to scale in this manner.
this is a transit validation mechanism, not a full-fledged legal signature 
mechanism.
the nature of the 'assurances' being offered are intentionally minimal.  the 
purpose of the finer-grained keys has more to do with management than it does 
with making strong assurances about the purported author.
  d/
  ---
  Dave Crocker
  Brandenburg InternetWorking
  +1.408.246.8253
  dcrocker  a t ...
  WE'VE MOVED to:  www.bbiw.net