diff --git a/assert-vars.yml b/assert-vars.yml
new file mode 100644
index 0000000..7395ccf
--- /dev/null
+++ b/assert-vars.yml
@@ -0,0 +1,8 @@
+- name: verify if vars are defined and not empty
+  assert:
+    that:
+      - "{{ item }} is defined and {{ item }}|length > 0"
+    fail_msg: "'{{ item }}' is not defined or empty"
+    success_msg: "'{{ item }} ' is defined"
+  with_items:
+    - mail_domain
\ No newline at end of file
diff --git a/defaults/main.yml b/defaults/main.yml
new file mode 100644
index 0000000..a70172d
--- /dev/null
+++ b/defaults/main.yml
@@ -0,0 +1,7 @@
+---
+#postfix
+#mail_domain: gmotech.dyndns.org
+#mail_relay_host: smtpauths.bluewin.ch
+#mail_relay_host: smtp.gmail.com
+# DNS
+#dns_domain_search: gmotech.net
\ No newline at end of file
diff --git a/main.yml b/main.yml
index 8e1c073..a08b2f4 100644
--- a/main.yml
+++ b/main.yml
@@ -1,2 +1,10 @@
 ---
-- hosts: all
\ No newline at end of file
+- hosts: all
+
+- tasks:
+  - include_tasks: assert-vars.yml
+#  - include_tasks: disable_ipv6.yml
+#  - include_tasks: hosts.yml
+#  - include_tasks: inst_packages.yml
+#  - include_tasks: misc.yml
+    
\ No newline at end of file