diff --git a/Doc/Sdi/icinga.xml b/Doc/Sdi/icinga.xml
index 4c57f644a1eab43fcc876cb3dec99bbb058dd3b1..95b4c0aa8b74a19c8aec6f94cce8a6413431137b 100644
--- a/Doc/Sdi/icinga.xml
+++ b/Doc/Sdi/icinga.xml
@@ -11,8 +11,8 @@
          xmlns:db="http://docbook.org/ns/docbook">
   <title>Icinga 2</title>
 
-  <para>With respect to newer modules you may want to install newer icinga2
-  packages provided by the <link
+  <para>With respect to more current modules you may want to install newer
+  icinga2 packages provided by the <link
   xlink:href="https://packages.icinga.com/debian/#indexlist">Icinga Debian
   package repository</link>.</para>
 
@@ -21,6 +21,34 @@
       <para><link
       xlink:href="https://www.howtoforge.com/tutorial/how-to-install-icinga2-on-debian-9">How
       to Install Icinga 2 Monitoring Tool on Debian 9.2</link></para>
+
+      <caution>
+        <para>Fix <code>admin</code> email in
+        <filename>/etc/icinga/conf.d/users.conf</filename> prior to starting
+        **any** <productname>Icinga</productname> related service:</para>
+
+        <informaltable border="0">
+          <tr>
+            <td valign="top"><programlisting language="none">object User "icingaadmin" {
+  import "generic-user"
+
+  display_name = "Icinga 2 Admin"
+  groups = [ "icingaadmins" ]
+
+  email = "<emphasis role="red">root@localhost</emphasis>"
+}</programlisting></td>
+
+            <td valign="top"><programlisting language="none">object User "icingaadmin" {
+  import "generic-user"
+
+  display_name = "Icinga 2 Admin"
+  groups = [ "icingaadmins" ]
+
+  email = "<emphasis role="red">yourEmail@whatsoever.org</emphasis>"
+}</programlisting></td>
+          </tr>
+        </informaltable>
+      </caution>
     </listitem>
 
     <listitem>