[xwiki-users] Borabora block emails to users@xwiki.org

Hi, All! I replied to one of the emails and received following: Reporting-MTA: dns; borabora.xpertnet.org Received-From-MTA: smtp; borabora.xwiki.com ([127.0.0.1]) Arrival-Date: Sun,  1 Feb 2015 09:42:57 +0000 (UTC) Original-Recipient: rfc822;users(a)xwiki.org Final-Recipient: rfc822;users(a)xwiki.org Action: failed Status: 5.7.0 Diagnostic-Code: smtp; 554 5.7.0 Bounce, id=29194-13 - spam Last-Attempt-Date: Sun,  1 Feb 2015 09:42:57 +0000 (UTC) Final-Log-ID: 29194-13/SfRQFeszKdSD How can I convince this Borabora, that I'm not spamming users(a)xwiki.org? Kind regards, Dmitry