[Mailman-Users] Bounce issues with Yahoo

Brad Knowles brad at stop.mail-abuse.org
Wed Mar 1 23:03:36 CET 2006

At 12:52 PM -0800 2006-03-01, Dragon wrote:

>  Why not disable those notification messages completely and discard the
>  incoming messages from nonmembers?
>  That is what I do on my lists.
>  My reasoning behind this is that if there is any mail from a nonmember,
>  99.99% of the time it's a spammer that has sent that message. By silently
>  discarding it, I am not confirming for them that there is a live e-mail
>  address there and (hopefully) reducing the number of attempts to spam the
>  address in the future.

	We've had this discussion in the past.

	On the one hand, responding to spoofed e-mail addresses is a form 
of blowback, and could potentially be considered spam in and of 
itself.  This behaviour could be easily abused by attackers to cause 
your mail servers to DoS anyone else they want -- all they have to do 
is generate garbage e-mail at high rates of speed in the name of 
their victim.

	On the other hand, not informing people that their posts are not 
being accepted to the mailing list (because they're not subscribed, 
or whatever) is guaranteed to cause you to lose legitimate messages. 
For example, if you run a mailing list intended to support the 
leading Free/Open Source Developers conference in Europe and you set 
up your list this way, you are guaranteed to get a lot of grief from 
various subscribers on the list because posts they made months ago 
were silently dropped and never went through.  Now that months have 
passed and they asked their question with a reasonable amount of time 
for a response, but the question never got through, well ... everyone 
is screwed.

>  Either way, it's not something that I care about nor is it something that I
>  believe needs an explanatory message sent back to the sender.

	If you accept that nothing important ever gets sent to the list, 
and that any message can be casually thrown away for any reason, then 
that's a reasonable response.

	Otherwise, you may have some tougher choices to make.

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/>.

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