spam from lists.opensuse.org ?

Hello, all my outbound emails to <listname>@lists.opensuse.org and certain inbound emails (the last ones are from Dan Čermák <dcermak@suse.com>, Gerald Pfeifer <gp@suse.com>, etc) end up flagged as spam by my mail provider (libero.it). On my side I've set no filter and blocked nobody. Libero claims  responsible for the wrong flagging being the opensuse's servers. I attach their response to my complain. Please check it and let me know. Best Regards, Mauro