Re: DoS and Replay protection for message signatures

> However, message signatures offer _no_  authenticated identifier prior to 
> resources being committed.

Such is the nature of message signatures in headers.  But, there are still 
substantial resource savings because, although you have to go as far as the 
DATA command and expend some bandwidth and disk (or RAM) to accept the 
message, you can always verify the signature before going any further.  In 
my MTA's case, DKIM can lead to the rejection of a message which represents 
SUBSTANTIAL resource savings because the message won't have to go through 
subsequent content-filtering (at the system and user levels), anti-virusing, 
or SpamAssassin'ating.

So, I didn't want people to have the impression that there are no resource 
saving benefits to DKIM implementations.  This is a quality of 
implementation issue, not a DKIM issue as others have said.

--
Arvel