On Wed, May 14, 2014 at 1:53 PM, L.W. van Braam van Vloten
<[log in to unmask]>wrote, in part​:

> I am analyzing the impact of the DMARC issue on my ListServ service
> (running on Linux).
>
> I am trying to determine if any Yahoo / AOL addresses have inadvertently
> been removed from any of my lists,
> ​ ...
>

​You need to relearn "the DMARC issue".  To get you started:

   - *Many* ISPs use DMARC, not just Yahoo and AOL.​
   - The problem is that Yahoo and AOL have set their DMARC configuration
   so that it tells all DMARC ISPs to reject mail that has a "From:" address
   from them, but is being sent from someone else.  This part is new.  Please
   note that other ISPs may do this in the future!
   - Your Listserv server will distribute posts with a "From:" field of the
   poster, unless it has been upgraded to level set "16.0-2014a" (build date
   is 23 April, 2014 for me).
   - Then, without the fix,  if the "From:" field is Yahoo or AOL, you have
   the start of "the DMARC issue", as
      - All DMARC ISPs, not just Yahoo and AOL, will reject the
      distribution. Exactly how each implements "reject" varies.
      - Some will drop the distribution into the recipients' spam folder.
      - Many will return a "permanent" error suggesting the recipient does
      not exist.
      - Some will return a "permanent" error that tells you (or your list
      owner) of a DMARC problem.
      - If your lists have automatic deletion, sooner or later, Listserv
      will terminate the subscriptions of everyone that has returned a
sufficient
      number of errors.
      - So, not only have your DMARC subscribers failed to receive
      distribution of posts made by Yahoo and AOL posters, but they
will probably
      lose their subscriptions.
      - My lists that had Yahoo and AOL posters lost large numbers of
      subscribers before we caught and addressed the problem.
   - What to do?   Upgrade to the recent Listserv level set asap.  Once you
   have done that, "the DMARC issue" is behind you, not to bother you or your
   list owners and subscribers again.
      - Until you get Listserv upgraded, you probably want to avoid
      distributing posts where the "From:" field contains a Yahoo or AOL
      address.  There are various ways to do this, but you won't like
any of them.
      - How to tell if subscription deletions have taken place or are
   immanent?  As Valdis suggests, this can be difficult.
      - If your lists have change logs, you have a record.   Look at each
      change log for subscription deletions and the reason, as well as
posts from
      Yahoo or AOL.  If you don't have change logs, why not?
      - On Linux, subscribers being monitored are listed in a server file
      with extension ".autodel".  Have a look; they are almost human readable.
      It helps to envision the format of the daily summary of errors a
list owner
      can receive.

Hope this helps!

Cheers, Wayne

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