Lots of bounce action notification received from mostly yahoo's suscribers

[Willy Ted Manga]

Hello,
I have noticed in Ubuntu-cm mailing-list that a lot of yahoo emails
address has been disabled by mailman. Does anybody know why we have
encountered this issue ?
In addition, most of these emails were not receiving last e-mails. I
have untick the flack [noMail] ; hope that It will be ok...

Here is a transcript of one "bounce action notification" and its
attachment.

List:       Ubuntu-cm
    Member:     <emailAdress>
    Action:     Subscription disabled.
    Reason:     Excessive or fatal bounces.
    


The triggering bounce notice is attached below.

Received: from Debian-exim by chlorine.canonical.com with local (Exim
4.69)
 id 1Nmsn7-0007eY-H9 for ubuntu-cm-bounces at lists.ubuntu.com; Wed, 03 Mar
 2010 17:55:25 +0000
X-Failed-Recipients: <SomeEmailAddressesHere>
Auto-Submitted: auto-replied
From: Mail Delivery System <Mailer-Daemon at chlorine.canonical.com>
To: ubuntu-cm-bounces at lists.ubuntu.com
Subject: Mail delivery failed: returning message to sender
Message-Id: <E1Nmsn7-0007eY-H9 at chlorine.canonical.com>
Date: Wed, 03 Mar 2010 17:55:25 +0000
Mime-Version: 1.0

-- 
Willy Manga
Ubuntu Cameroon
https://launchpad.net/~manga-willy