updated role for debian buster wich dropped ssmtp

tasks/nullmailer.yml

@@ -0,0 +1,12 @@
+- name: install nullmailer
+  apt: pkg=nullmailer state=latest
+
+- name: setup nullmailer
+  notify: restart nullmailer
+  copy:
+    dest: "{{ item.dest }}"
+    content: "{{ mail.root }}"
+  with_items:
+  - {"dest": "/etc/nullmailer/adminaddr",     content: "{{ mail.root }}"}
+  - {"dest": "/etc/nullmailer/remotes",       content: "{{ mail.root }}"}
+  - {"dest": "/etc/nullmailer/defaultdomain", content: "{{ mail.domain }}"}