[H-GEN] Humbug is now Greylisting mail

Greg Black gjb at gbch.net
Mon Mar 6 06:27:16 EST 2006


On 2006-03-06, Bruce Campbell wrote:
> On Mon, 6 Mar 2006, Greg Black wrote:
>> On 2006-03-05, Bruce Campbell wrote:
>> 
>>> In the Humbug setup, there is a slight twist, in that email sent to the
>>> list addresses will be immediately accepted if it is from a recognised
>>> subscriber to that list.  Note that this test is performed on the SMTP
>>> MAIL FROM field, and not on the not-yet-received 'From:' address in the
>>> mail data.
>> 
>> This test is either unimplemented at present or is implemented
>> incorrectly.
> 
> Neither I'm afraid; a classic case of a working test not being used due to 
> an earlier test issuing the defer message.  One slight reworking of the 
> test order later, and the intended behaviour works (I've removed your 
> entries from the greylisting db so you can catch me out again ;) )

Fair enough.  I mainly wrote my original message to alert you to
the need to fine tune it, so I'll watch this one as it goes and
see what happens.

>> I don't use greylisting because of the collateral
>> damage of this type.
> 
> This is where we need to balance speed of delivery against cost of 
> receiving the email.  Humbug is not a business and, imho, does not have a 
> pressing need for immediate delivery, but Humbug does have to pay for its 
> expenses, such as traffic received.

I'm not here to debate whether or not the Humbug mail servers
should use greylisting, as that's not my call and it's within
the normal prerogatives of those responsible to make those
decisions without worrying about the noise from the cheap seats.

However, since I'm pretty certain that many Humbug members won't
fully understand the way this stuff works, I'm just going to
toss in a few more bits of information.

While it's true that there's no business case to be made for
fast delivery to Humbug lists, there are circumstances where
delays make the whole thing less good for everybody.  As one
example, when somebody posts a standard Unix FAQ to H-Gen, the
optimal outcome (as I see things) is for whichever geek who
happens to be monitoring her mail to fire off a short, correct,
reply and then we're done.  But if one or more of those instant
answers is delayed, the question is likely to be answered way
too many times for comfort.  (I know this case is not compelling
as an argument against greylisting and I'm not advancing it as
such; my goal here is merely to show that timeliness is of some
importance to us.)

>> Yes, I understand the desire to reduce spam levels, since that
>> is a constant battle that I have to wage as well.  But I will
>> always whine when what I consider ill-conceived attempts to do
>> that result in my email being delayed or rejected.  This is one
>> of those whines.
> 
> The only time email will be rejected by the greylisting process is when 
> the sending MTA gets the meaning of 'temporary' confused with 'permanent'.

My MTA would never make that mistake and I would have very
little sympathy with one that did.  But there is a gotcha, all
the same:

> Delays are far more common, and is an unavoidable side effect of 
> Greylisting.  However, the delay is only on the first instance; following
> mails from matching tuples are passed through much quicker.

That's only true when the same MTA retries.  Big organisations
that use round robin MTAs to handle outgoing email may well get
delayed so much (as each server that makes an attempt gets told
about a temporary failure) that they might eventually bounce the
message when it exceeds some time limit in the queue.

Since I need to be able to receive legitimate email from anybody
and don't care to have to keep up to date on yet another detail,
I'm not willing to try to handle whitelisting those big senders,
but that would be essential if I were to consider greylisting.

Anyway, thanks for the explanations of the intended operation of
the greylisting.  I hope members now know as much as they need
to.  And, in case people still need more info, don't forget the
sources of info on the web.

Cheers, Greg




More information about the General mailing list