Subject: Re: RE: [Asrg] Some data on the validity of MAIL FROM addresses

From: "Jon Kyme" <[email-masked]>
Date: Tue, 20 May 2003 17:22:48 +0100

> At 4:25 PM +0100 5/20/03, Jon Kyme wrote:
> >Sorry, what? Your justification for not doing BCP is that it's
> >"non-trivial" to do it on the software you've chosen?
> 
> 
> There are far more reasons to choose a piece of software than just 
> it's external interface.

I can't imagine a good technical reason for picking software that makes it
practically impossible to do the job to the same standard as BCP, given the
choice that exists.
I know there are often good political reasons why these irrational choices
are made - that's a somewhat different matter.

Anyway (back to the original point), Hotmail seems to do better than Yahoo
on the specific issue (response to RCPT TO <non-existent-rcpt>) we were
discussing. It's clear that some operators can do this on very large
distributed systems. Others can't - or won't.

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From: Kee Hinckley <[email-masked]>
Date: Tue, 20 May 2003 14:04:57 -0400

>practically impossible to do the job to the same standard as BCP, given the

Well, I replied off list because I didn't think this was on topic. 
But I'm just pointing out that we're looking at this from a problem 
of how mail systems interoperate with each other.  When you're in a 
company buying a mail system, your concerns are:
	- ease of maintenance
	- ease of use for users
	- functionality for users
	- how it works with other systems
The order may vary, but the last one is almost always going to be 
last.  Furthermore, it *looks* like a check-off item.  That fact that 
some mail systems "don't play well with others" doesn't come out 
until it's *way* too late.

>distributed systems. Others can't - or won't.

It could well be a "won't".  By deferring the reject until after the 
DATA command you make it very difficult to probe for valid addresses 
to spam.
-- 
Kee Hinckley
http://www.messagefire.com/          Junk-Free Email Filtering
http://commons.somewhere.com/buzz/   Writings on Technology and Society

I'm not sure which upsets me more: that people are so unwilling to accept
responsibility for their own actions, or that they are so eager to regulate
everyone else's.
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From: "Jon Kyme" <[email-masked]>
Date: Tue, 20 May 2003 20:46:58 +0100

Kee mailed me off-list and correctly pointed out that much of what I was
saying wasn't really relevant.

But part of his response is on topic so I've taken the liberty of bringing
it back to the list.

> DATA command you make it very difficult to probe for valid addresses 

No, you don't make it difficult for spammers. They will send some data.
You only make it difficult for people attempting to verify addresses
without sending data; so-called "SMTP callback" for instance, or when
trying to verify a list of addresses for research purposes :-)