[Mailman-Users] Sudden Disabled/Unsubscribed list members?

[Stephen J. Turnbull]

Mark Sapiro writes:
 > On 06/06/2016 03:10 AM, Karl Smith wrote:

 > > Recently, my CAMRA Members list (the biggest one with about 700
 > > email addresses) has stopped sending me a bounce copy and has on
 > > two occasions rejected one of my messages and unsubscribed a
 > > large (apparently random) number of the members, including me one
 > > time.

 > This could be a DMARC issue. Particularly if only around the time this
 > started, a user or users started posting From: a yahoo.com or aol.com or
 > other address with a domain publishing a DMARC p=reject policy or if you
 > have regular posters in any of the yahoo.fr, yahoo.jp or other 'foreign'
 > yahoo domains as these recently also started publishing a DMARC p=reject
 > policy.

That's what it sounds like to me, too.  And it could be *any* address,
not restricted to yahoo.* or aol.com -- there are many corporate
domains (especially banks etc) that publish p=reject, and I get the
feeling that it's spreading (slowly so far, though).  As Mark says,
you're looking for somebody who just started posting, or restarted
posting after a layoff of several months, about the time the bounces
and unsubscriptions started.  If you have access to the "host" or
"dig" utilities, you can check yourself by looking at the users'
addresses, taking only the domain (the part after the "@" mark),
prepend "_dmarc.", and checking for a TXT record (see examples
below using "host" if you're interested, if not, that's no sin :-).

@Mark BTW yahoo.co.jp and yahoo.jp are not in that set (warning: black
magic follows, except for Mark you are not expected to understand this
but I'll explain if you want -- new thread please :-):

$ host -t TXT _dmarc.yahoo.jp
Host _dmarc.yahoo.jp not found: 3(NXDOMAIN)
$ host -t TXT _dmarc.yahoo.co.jp
Host _dmarc.yahoo.co.jp not found: 3(NXDOMAIN)
$ host -t TXT _dmarc.yahoo.ne.jp
_dmarc.yahoo.ne.jp descriptive text "v=DMARC1\; p=quarantine\; rf=afrf\; rua=mailto:ymail_dmarc_report at yahoo.ne.jp\; ruf=mailto:ymail_dmarc_report at yahoo.ne.jp"
$ host -t TXT yahoo.co.jp
yahoo.co.jp descriptive text "v=spf1 include:spf.yahoo.co.jp ~all"

My guess is that yahoo.ne.jp is used as the "canonical" domain for
Yahoo! Japan's domain hosting service.  Japanese Yahoo! users have
mailboxes at yahoo.co.jp AFAIK.

 > > Note that I am not a computer or software expert and only use basic
 > > functionality.
 > 
 > I can understand that and I am not unsympathetic, but even if you are
 > non-technical, it helps a lot to describe exactly what you see. We will
 > try to help, but at some point, the people who administer the Mailman
 > installation may need to be involved

+1 to all Mark says here.  So far Mark and I are reduced to guessing,
we need more data.  We do not blame the victim, but we do need your
help as best you can give it to diagnose the problem.  Sort of like a
doctor working with a foreign patient -- you do your best, we do ours,
and we'll work it out together.

Steve