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Re: Server Enforcement of Time Blocks (wait=)

2011-10-28 21:40:52

On Oct 28, 2011, at 7:11 PM, Hector Santos wrote:

Steve Atkins wrote:

My point is if like Atkins proposal and might implement it, once you do, 
you will be behaving like a Greylisted server.
That's simply not true. Please stop stating that.

Are you saying your proposal offer a server issuing of a "wait=" time with no 
server tracking and enforcement?

Yes. It's purely a protocol for the server to communicate to cooperative 
clients. I foresee the primary usage to be not enforced by the server, 
certainly not on a real time basis, though it's something that would be quite 
usable if the server were tracking clients in that way.

Its not be meant to be a negative and it doesn't help with ongoing attempts 
to create division.

Any proposal that includes a "time delay" for a client to use, and more 
importantly the server will enforce, is 100% *behaving* (keyword) like a 
Greylisting Server model.  I can't see how you can avoid it.

Actually it's not, but that's a different issue. (Greylisting requires keeping 
track of remote clients in some way, so as to treat them differently the first 
time you see mail from them. As a concrete example of a server enforcing delays 
that's not greylisting consider a mailserver with a database backend, where you 
need to take the backend down for maintenance for a few minutes. While the 
database is down, the server may respond to any transaction with a 4xx (or even 
with a 4xx wait=<number of seconds until the database server comes back 
online>). Attempted redeliveries before that will be deferred again.)

The client is doing this blinding.  If it encounters a server with this 
"wait=" in a 4yz response, its going to have the same MTA software 
rescheduling code for supporting any other kind a "retry=" or parsing of the 
informal existing greylisting servers with their time hints.

So unless the proposal is not offering server enforcement, it is very much a 
Greylisting Model.

It's a traffic management enhancement. It could certainly benefit a greylister, 
but it's of broader value than that narrow niche.


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