[Mailman-Developers] suggested improvement for Mailman's bounce processing

[Brad Knowles]

At 3:08 PM -0400 2006-08-07, James Ralston wrote:

>  Perhaps, but we cannot solve this problem, and there's a fine line
>  between working around stupidity and coddling it.

Right, but if we can't fix the problem of the multitude of broken 
MTAs out there, and the fact that most of them probably don't assign 
the appropriate extended response codes in accordance with the RFCs, 
then the likelihood is that we are going to be lead to make the wrong 
guesses based on the response we get.

I think the question is how damaging are those wrong guesses, and as 
compared to not making any attempt to guess one way or the other and 
just treat all bounces as the same?


Without any further detailed information, my gut feeling is that 
we're better off not trying to guess what the real reason was for a 
given bounce, but to just treat them all the same and to give enough 
lattitude that people don't get unsubscribed with just a single 
bounce (or whatever).

>  What further data do you wish to see?  I think I've documented the
>  problem well enough.  There's no way we know many horribly broken
>  sites are out there.

Save a copy of each and every bounce you get over an extended period 
of time (this may require modifications to the source code), and then 
try to categorize them by the easy-to-parse numeric response code 
versus the harder-to-parse description, and actually find out how the 
cookie crumbles.


Describing the one particular type of sub-problem that you've run 
into doesn't really help us in this situation, not when you're 
talking about changing the behaviour of an entire subsystem in order 
to accommodate your one specific issue.

Instead, you need to go on a quest to obtain large amounts of data 
that demonstrate how easy (or hard) it is to determine the real 
reason why some message bounced and then figure out how you can take 
that information and modify the source code to suit.

>  Right: the only risk is that bounces coming from a subscriber at a
>  broken site might be ignored, because they look like they're being
>  generated based on the content of certain messages.

I'm not convinced that's the only risk, and I'm not convinced that 
the potential consequences are that minor.  But if you can provide 
sufficient evidence to show that you are correct, at least for the 
users on your site, I'm willing to be convinced.

>  IMHO, this risk is negligible.  If the operators of the broken site in
>  question get annoyed that Mailman keeps trying to send messages to a
>  non-existent address, they should fix their broken site.

Well, if the windmill turns out to be Microsoft, you might want to 
seriously think about whether or not you really want to continue 
trying to tilt at that thing.

You might want to look into how big this problem could potentially 
be, before you decide to just casually blow off any possible 
consequences.

-- 
Brad Knowles, <brad at stop.mail-abuse.org>

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."

     -- Benjamin Franklin (1706-1790), reply of the Pennsylvania
     Assembly to the Governor, November 11, 1755

  Founding Individual Sponsor of LOPSA.  See <http://www.lopsa.org/>.