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Comments on: draft-melnikov-smtp-priority-02

2011-07-11 17:36:23

Comments on: draft-melnikov-smtp-priority-02
SMTP Extension for Message Priorities


Section 2, last paragraph:

Seems to be self-contradictory. Either there are enough resources to 
cause an email to be "ready to be sent" or there aren't!


Section 3, item 5:

This seems to reject that PRIORITY 0 should mean "Normal"


Section 4.2, next to last paragraph:

I believe that the recommendation should be stronger, at least a 
"SHOULD". There must be some cost to using (non-negative) 
PRIORITY. This will guard against abuse. Otherwise, how do you 
deter spammers from always using PRIORITY 99?

Another thing to worry about is that this becomes a new Denial-
of-Service mechanism if not controlled in some way.

Either authentication, SPF (RFC 4408) or similar should be used 
before PRIORITY is allowed.


Section 4.2, last paragraph:

   "priority (both to lower or to upper it)."
   
 Perhaps:
 
   "priority (both to lower or to raise it)."


Section 4.3, Item 1:

I think that this means that a message received with with NO 
priority indication (thus "normal") MUST be relayed with a 
PRIORITY 0 parameter. This seems overly stringent.

Also, does this paragrah mean that if an MTA only implements the 
suggested 6 priority levels, a message received with, e.g., 
PRIORITY 93 MUST be relayed with a PRIORITY 93 parameter? This 
seems reasonable, but the text is not quite clear.


Section 4.6, item 2:

What is needed is some sort of meaning specified for the 199 
possible values that does not require reference to other mutually 
inconsistent priority schemes. 

E.g., MMHS: -20 = routine, 0 = priority. Really?

So, does "PRIORITY 50" mean:

   "You should probably read this first"
or:
   "CAP'N SHE'S GONNA BLOW!"?


Section 5.1:

Since the vast majority of messages will either be marked as
"PRIORITY 0" or presumed to be priority 0, is there any mechanism
to prevent starvation for those messages marked at a negative
priority? Note that for a high volume MTA there would likely
always be SOME priority 0 messages in the queue which would
preclude sending ANY messages at a lower priority.


Section 5.1, paragraph 3:

The first sentence is unclear. It seems to have *emails* being 
forbidden to initiate tranactions. I would expect MTAs to be the 
object of any restrictions.




-- 
Bill McQuillan <McQuilWP(_at_)pobox(_dot_)com>