Hey Guys and Girls, I'm having a strange issue which I cannot solve by myself: Every night I'm getting mails to the root account (around 3am): Message 1: From root@server1.xxxxxx.de Mon Feb 5 03:02:43 2018 X-Original-To: root@server1.xxxxxx.de X-Virus-Scanned: Debian amavisd-new at To: root@server1.xxxxxx.de From: root@server1.xxxxxx.de Auto-Submitted: auto-generated Subject: *** SECURITY information for xxxxxx.servers.jiffybox.net *** Date: Mon, 5 Feb 2018 03:02:28 +0000 (UTC) xxxxxx.servers.jiffybox.net : Feb 5 03:02:28 : root : unable to resolve host xxxxxx.servers.jiffybox.net I'm running Ubuntu Server with ISPConfig installed and until now (this issue might be since beginning...) without problems I found at all. I tried to ping the host mentioned above with success. Furthermore I searched for dirs in: /var/vmail/ and just found my domains running on the server. May there somehow lie the mistake? Where should I start looking? Cheers, Bent