Hi there,



> -----Original Message-----

> 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,



We have had 10s and 10s of people removed from one of our larger lists (tiny I suspect compared with some of you) because

Yahoo senders are posting to the list and we have a sizeable number of Hotmail subscribers, many of whom have been removed more than

once. That's the simple impact of DMARC and mailing lists.



Alan Thew



> 	​ ...

> 

> 

> ​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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