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Re: Messages to Python-List aren't posting

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  Re: Messages to Python-List aren't posting Skip Montanaro <skip@pobox.com> - 2013-07-19 09:57 -0500
    Re: Messages to Python-List aren't posting Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-19 16:31 +0000
      Re: Messages to Python-List aren't posting Chris Angelico <rosuav@gmail.com> - 2013-07-20 02:41 +1000

#50910 — Re: Messages to Python-List aren't posting

> Is it possible that the name "Matthew
> Lefavor" has been added to a greylist or something?

That's not how greylisting works.  Greylisting is a scheme used to
eliminate spam.  The server knows what email addresses it's received
mail from in the last little while (say, the last month).  When it
gets a message purporting to be from someone not in its little
database (say, user@somewhere.com) it responds with a "try later"
message.  Legitimate mail will be delayed for a few minutes.  The
sending SMTP server will try again, and the message will be accepted
by the receiving server. That server will also record
user@somewhere.com as a "known" address.  The theory behind
greylisting is that a spambot either won't come back and retry sending
(it's going millions of messages to flood the net with, and can't be
bothered to retry mail) or will be found and shut off by ISPs before
the delay period expires.

> One relevant piece of information: I have subscribed and unsubscribed to
> different combinations of these lists several times over the past year, and
> particularly over the past few months (as I was trying to manage the flow of
> emails to my filter-less work inbox.) Could that sort of behavior associate
> my name with malicious intent?

I wouldn't think so.  More likely, you might have made a mistake in
your configuration parameters.  You might want to double-check your
python-list@.python.org subscription information in Mailman to make
sure you haven't inadvertently done something.  If the problem
persists, send a note to postmaster@python.org describing the problem,
and include a message (with all its headers intact) that demonstrates
the problem, as Chris did with the timestamps.

Skip

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#50915

On Fri, 19 Jul 2013 09:57:47 -0500, Skip Montanaro wrote:

>> Is it possible that the name "Matthew Lefavor" has been added to a
>> greylist or something?
> 
> That's not how greylisting works.  Greylisting is a scheme used to
> eliminate spam.  The server knows what email addresses it's received
> mail from in the last little while (say, the last month).  When it gets
> a message purporting to be from someone not in its little database (say,
> user@somewhere.com) it responds with a "try later" message.  Legitimate
> mail will be delayed for a few minutes.  The sending SMTP server will
> try again, and the message will be accepted by the receiving server.
> That server will also record user@somewhere.com as a "known" address. 
> The theory behind greylisting is that a spambot either won't come back
> and retry sending (it's going millions of messages to flood the net
> with, and can't be bothered to retry mail) or will be found and shut off
> by ISPs before the delay period expires.


Greylisting is great, but there are a couple of quirks, as the company I 
work for discovered the hard way. Some ISPs don't follow the rules. I'm 
not talking about dinky little ISPs run by some guy in a basement, I'm 
talking some of the biggest ISPs in Australia like Optus or Bigpond. They 
either completely ignore the "try later" message, and report it as a hard 
failure, or they wait a full day before trying again instead of a few 
minutes. Or, if they do try again, they try again from a different mail 
server, so the greylisting software sees a different sender/server 
combination, and greylists that as well.

Admittedly, this was a few years back that we ran into this problem, and 
since then we've just routinely whitelisted email from Optus and Bigpond, 
curse their black souls for making spam prevention just that little bit 
harder. So I suppose it's possible that they've stopped being bad actors 
and started following the standards correctly.

No really, stop laughing, it is technically possible.



-- 
Steven

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#50916

On Sat, Jul 20, 2013 at 2:31 AM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> Admittedly, this was a few years back that we ran into this problem, and
> since then we've just routinely whitelisted email from Optus and Bigpond,
> curse their black souls for making spam prevention just that little bit
> harder. So I suppose it's possible that they've stopped being bad actors
> and started following the standards correctly.
>
> No really, stop laughing, it is technically possible.

Once you've worked in networking long enough, you cease to be
surprised when things go right. Anything is possible... even
standards-compliant behaviour.

ChrisA

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