Re: [Asrg] IM2000

[Devdas Bhagat <devdas at dvb.homelinux.org>]

On 24/04/04 14:56 +0100, cw wrote:
> Hi folks,
> I have been doing a lot of digging around with various anti-spam proposals
> and one thing that crossed my mind is in relation to IM2000.
> (http://cr.yp.to/im2000.html)
> Incase there is anyone here unaware, IM2000 essentially proposes pushing
> the message queues back to the sender so that people closer to the
> recipient do not have to pay and those closer to the sender are given
> more motivation for doing something about the sender.
> The proposal would require some significant infrastructure overhaul as
> would many to get it implemented, but (and I am just thinking on my feat
> at the moment) would it be possible to overlay something based on this
> onto the existing infrastructure?
What about offline hosts? And when does the local copy get deleted?

> 
> To expand, if your incoming mailserver rejects all inbound messages with
> a transient error and notifies the recipient. The recipient can then
> elect to allow any similar messages through if the remote server tries
> again within a set period of time.
A variant on greylisting with human intervention.

> This may have to second guess how many times the remote server will retry
> before giving up, and either allow or reject the message with a permanent
> error if the recipient does not express their will in time.
A (mis)feature which greylisting avoids by allowing mail through on the
second try.

> 
> Either way, if the message is legitimate but ends up being bounced, a
> clear message could indicate why and recommend trying again or contacting
> the user via other means to arrange to allow the message through.
> 
> What are the implications of running a system like this other than
> having to develop a frontend for local users?
Avoid the frontend by using greylisting. The effect that this has had is
that spammers use full fledged SMTP servers to spam, rather than open
proxies. It hasn't had much real benefit, but greylisting was useful.

Devdas Bhagat

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