Re: SMTP traffic control

Carl S. Gutekunst wrote:
> Hector Santos wrote:
> > > Unfortunately, the dominant conversation seems to be around an SMTP 
> > > response that only applies to greylisting. I'd never use that or 
> > > support it, it's such a teeny-tiny corner case, especially in the 
> > > B-to-B world where I live.
> > Does this suggests that your B2B market is oblivious to the outside 
> > world remote server behaviors employing 4yz temporary rejections?
> They're highly conscious of 4xx temporary rejections associated with 
> resource exhaustion and down systems. But in 20 years of supporting 
> B-to-B E-mail, I can only remember one issue with someone else's 
> greylisting -- and that was because it was broken.
Ok, and we should|must all respect that.  Nevertheless, its not the 
case for all though, nor should it be reason for not considering this. 
 It just means it doesn't apply to your market area.
My point is if like Atkins proposal and might implement it, once you 
do, you will be behaving like a Greylisted server.
Most better SMTP servers already deal with DoS related issues and 
employ a concept for loading limiting/restrictions.  What has been 
seen with some real servers 421 responses today, and now also being 
suggested is adding "time delay" hints to this load limiting 421 
rejections because it is also behaving like a Greylisting server.
Again, for lack of a better term, Greylisting, is really two parts:

 - Using 4yz for unknown, non-whitelisted, unrecorded senders 
immediately,
 - Blocking them for a specific, implementation based time length.

If we remove the blocking time from the equation, i.e. it was never 
part of the logic, then I don't believe we would be having this 
discussion.  All 2nd tries will work and delays will be limited to the 
MTA's 2nd attempt time.
But thats not the case. The issue is that is there are blocking times 
and in comes in varying degrees and implementing Atkins proposals 
pushing you into something you indicated you don't wish to support.
Look, I think both proposals are ok.  We do need something that 
documents Greylisting because its more than just issuing a "time 
delay", it about monitoring and tracking and using blocking times.
I could change the SMTPGREY proposal to use "wait=" which would 
reference a more "Generic" proposal on Server/client waiting times.
I would rather that we work together to seek a common solution to all 
the issues and needs, rather than begin starting and playing this 
partisanship games once again.
--
Sincerely

Hector Santos
http://www.santronics.com