[Mailman-Developers] thoughts on bounce processing

[Brad Knowles]

At 1:24 PM -0400 2006-05-11, James Ralston wrote:

>  The more I think about this, the more I think that silently discarding
>  bounces is an error.

	Mailman doesn't silently discard bounces.  It keeps a counter, 
and for each day that a bounce is received, that counter is 
incremented.  Multiple additional bounces on a single day do not 
cause the counter to be incremented, but they are still examined.

>                        While some bounces are irrelevant (e.g. vacation
>  messages), in the majority of cases, bounces are information that some
>  entity should act upon.  There should be two (and only two) options:
>
>      1.  Mailman processes all bounces.
>      2.  All bounces are forwarded to the list administrator(s).

	In your example above, that would only be appropriate if the AA 
is the list administrator.  I think a better method would be to have 
all bounces sent to the poster, regardless of who that poster is.  If 
it's an announcement-only list, then presumably you have a restricted 
set of people who can post to that list, and any one of them should 
be able to handle bounces sent directly back to them.

	This would imply that the envelope sender is left unmodified by 
Mailman, and that could potentially cause problems with things like 
SPF or DKIM, which the sender would need to be aware of.

	And hopefully you wouldn't use this kind of mechanism on an 
announcement-only list with thousands of recipients.


	That said, I can see that this would be a reasonable enhancement 
to request.

>  If list admins *really* want to (effectively) discard all bounces,
>  they can e.g. set bounce_info_stale_after to 1 and then set
>  bounce_score_threshold to something impossibly high (e.g. 500,000).

	Keep in mind that I've seen mail loops quickly spin into the 
thousands in a matter of minutes, especially when the messages are 
passing through systems that scrub what they consider to be 
non-useful headers like "Received:".

	I don't know that there's much of anything you could do about 
such loops.  I think the only thing I'd say here is that I'd tend to 
be a little more conservative in terms of what I'd call "impossibly 
high".  ;)

-- 
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

  LOPSA member since December 2005.  See <http://www.lopsa.org/>.