[Mailman-Users] Avoiding DMARC unsubscribes by enabling VERP_PROBES

Stephen J. Turnbull stephen at xemacs.org
Sun May 18 16:28:15 CEST 2014

Peter Shute writes:

 > Why isn't this the default setting? Is there some disadvantage to
 > it?

Until now, you only needed it when one of your peers was seriously
broken.  DMARC p=reject now means that AOL and Yahoo! are breaking
other hosts en masse.

Disadvantage, yes.  It requires resources from hosts which aren't
broken, both yours and those of completely innocent third parties
whose only "crime" is to participate in mailing lists on your host.
It covers up the fact that the messages that bounce are also wasting
your and third parties' resources.  *These* resources are significant,
because they involve cryptographic checks on whole messages, messages
which are typically already bloated by a factor of 5 or so by HTML,
and sometimes much more by "cute" background images and the like.

We really really want to stop these bounces in their tracks.
*Everybody* does; they do not help anybody.


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