From the looks of it, it seems yahoo emails are being rejected (Florence confirmed that all email messages that triggered the bounce, are @yahoo.fr ). So far, emails from a yahoo account to mailman ended up in spam filters of gmail recipients because of this anti spoofing policy at yahoo. It may be that they are now all being bounced instead of marked as spam? Those bounces then end up at mailman, which thinks the recipient that sends a bounce, is no longer valid. 

Not sure what would be the solution, other than people moving away from yahoo. 

Lodewijk

On Sun, Jul 16, 2017 at 3:23 PM, Florence Devouard <wmf-l@anthere.org> wrote:
Hello

The owners of the list just received a collection of notifications from mailman@lists.wikimedia.org

Topic: Bounce action notification

Typical message received

This is a Mailman mailing list bounce action notice:

    List:       Wikimediafr
    Member:     an email address
    Action:     Subscription disabled.
    Reason:     Excessive or fatal bounces.
    


The triggering bounce notice is attached below.

Questions? Contact the Mailman site administrator at
mailman@lists.wikimedia.org.

------

The attached document features

Sujet :
Mail delivery failed: returning message to sender

De :
Mail Delivery System <Mailer-Daemon@fermium.wikimedia.org>
Date :
16/07/2017 14:09
Pour :
wikimediafr-bounces@lists.wikimedia.org


This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

  An email address
    SMTP error from remote mail server after end of data:
    host gmail-smtp-in.l.google.com [173.194.66.27]:
    550-5.7.1 Unauthenticated email from yahoo.fr is not accepted due to domain's
    550-5.7.1 DMARC policy. Please contact the administrator of yahoo.fr domain if
    550-5.7.1 this was a legitimate mail. Please visit
    550-5.7.1  https://support.google.com/mail/answer/2451690 to learn about the
    550 5.7.1 DMARC initiative. r67si3673368qkr.391 - gsmtp

  An email address
    SMTP error from remote mail server after end of data:
    host gmail-smtp-in.l.google.com [173.194.66.27]:
    550-5.7.1 Unauthenticated email from yahoo.fr is not accepted due to domain's
    550-5.7.1 DMARC policy. Please contact the administrator of yahoo.fr domain if
    550-5.7.1 this was a legitimate mail. Please visit
    550-5.7.1  https://support.google.com/mail/answer/2451690 to learn about the
    550 5.7.1 DMARC initiative. r67si3673368qkr.391 - gsmtp

etc. etc. etc.

At the end of all of which, I see

------ This is a copy of the message, including all the headers. ------

Return-path: <wikimediafr-bounces@lists.wikimedia.org>
Received: from localhost ([::1]:36576 helo=fermium.wikimedia.org)
	by fermium.wikimedia.org with esmtp (Exim 4.84_2)
	(envelope-from <wikimediafr-bounces@lists.wikimedia.org>)
	id 1dWiMp-0004Q5-F6; Sun, 16 Jul 2017 12:09:43 +0000
Received: from sonic303-23.consmr.mail.ir2.yahoo.com ([77.238.178.204]:41383)
 by fermium.wikimedia.org with esmtps
 (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2)
 (envelope-from <omorand@yahoo.fr>) id 1dW8AO-0005kw-U0
 for wikimediafr@lists.wikimedia.org; Fri, 14 Jul 2017 21:30:29 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.fr; s=s2048;
 t=1500067827; bh=H0kKlQUk5veAFbi03/U9y+O19wVtODUQh3qxSVcacZk=;
 h=Date:From:Reply-To:To:Cc:Subject:References:From:Subject;
 b=o5jowvpe5tn4x6xMBXvjwoJuwMsrmu9BXygb+TXyWCoCX27aOoq2OmCl5vH3kE1fEdyF78ABFmZ+GflVUv1mjgz7zbjtHcuaFRC4XMI7NdFTle2sPwBZV+QRzka07uFFJ1+HgHDTGeaCMy5FhU9F4u3227XNYShb/CJ9ktPw74izlXvnBtyPmVwbomKq0I92pyXtA9ZZjL65Kv3pANQkPRjz0ou37JPbdOfsuZh5picX5/0s+61Lg5oKbqDHyzHWJwM9iaJ9ThuDHxYRP8zp0z4CyacDs1spr8tVsYpKTxYkOY5Ye4eDbQgVYTj0kqUG8whmCMZIm1ZD4OMg1d8Fyw==
X-YMail-OSG: uoV.n9oVM1lxp3LakqZ_JxzYgcLqTcH2LbGw.iOAoaMcqq7TACkLGMBF6zQymA.
 q8P2mKlAGOLjLOshr_G5Mg6Nr4ASIkQ.41ScEtYvzSBfxQJv2OQJwfD85PeHFjmpwGrPsuMZ67QL
 INHDHNH4JW6ML4BwihSoRVYlMLooTLRcj0uK5wyQzCit8gzyGMH7xW3nR6aoTTuqtAJ2CtcOfxHF
 4hhR7uAh5Nj5CEsrUIOINxjmy1Sx0W6Tqby58pdDlXVUjMZqm2pkPt8N0M6UIi4kxoNEyg6rdxRw
 7sYl54M8T5F6vxST.d0SOhHw8.Wvp7ldOY1HUB8rUc.keTG.BMVxjWnW0ITIscp3U5tPs5EyL4PH
 u.HBhVlT4rKqMmZycCLLWS.ACpDKZNAgXzKfH9fwzkYYowvgxfamkZFfcHPJTT2Y23lqDwbm7rRX
 4A5OQw2WeLAY0MSVAahDKHj5dgPolb9ltnKvXIk0CaImH8xgfNZESeKILW1WnicQ8ABdv48GFZcC
 ZxHR8v3eJqreQBpLCpTSJQ8y3VdrmeMEPESlLwDDpcJdBDu.z8DNsEOhuOEYOjYwggrOBtL2Zme.
 vMx9rZphbnEvtGREpVRVLjj5YhqUGc1dzUx0s6Uqm_7fbRIRTpsA8GPSdvGB7R0j9a5.rrDRYTZn
 jfmxq5z76
Received: from sonic.gate.mail.ne1.yahoo.com by
 sonic303.consmr.mail.ir2.yahoo.com with HTTP; Fri, 14 Jul 2017 21:30:27 +0000
Date: Fri, 14 Jul 2017 21:30:26 +0000 (UTC)
From: Olivier Morand <omorand@yahoo.fr>
To: Wikimedia France Public Mailing List <wikimediafr@lists.wikimedia.org>
Message-ID: <1875202748.906589.1500067826867@mail.yahoo.com>
MIME-Version: 1.0
References: <1875202748.906589.1500067826867.ref@mail.yahoo.com>
X-Mailer: WebService/1.1.10092 YahooMailNeo Mozilla/5.0 (Windows NT 6.3; WOW64;
 rv:54.0) Gecko/20100101 Firefox/54.0
Content-Length: 9571
X-Mailman-Approved-At: Sun, 16 Jul 2017 12:09:41 +0000
Subject: Re: [Wikimediafr]
	=?utf-8?q?missions_du_CA_=28was=3APr=C3=A9paration_?=
	=?utf-8?q?de_l=27AG=29?=
X-BeenThere: wikimediafr@lists.wikimedia.org
X-Mailman-Version: 2.1.18
Precedence: list

etc...


------------------

I have no idea what it means. I have no idea what to do. HELP !


Anthere


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