[CentOS] Mailing List "mail forwarding loop"

I've been getting over the last months several of these notices. Sometimes a few per day. What's the problem? Can't this be avoided?

This is the mail system at host mail.centos.org.

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to <postmaster>

If you do so, please include this problem report. You can delete your own text from the attached returned message.

The mail system

centos@centos.org: mail forwarding loop for centos@centos.org

Final-Recipient: rfc822; centos@centos.org Original-Recipient: rfc822;centos@centos.org Action: failed Status: 5.4.6 Diagnostic-Code: X-Postfix; mail forwarding loop for centos@centos.org

Kai