moved more to nullmailer

defaults/main.yml

@@ -2,3 +2,4 @@ mail:
   root: "root@example.com"
   server: "mail.example.com"
   domain: "example.com"
+  backend: nullmailer

tasks/main.yml

@@ -1,4 +1,6 @@
 - include_tasks: ssmtp.yml
-  when: ansible_distribution_release == "stretch"
+  when:
+  - ansible_distribution_release == "stretch"
+  - mail.backend == "ssmtp"
 - include_tasks: nullmailer.yml
-  when: ansible_distribution_release != "stretch"
+  when: (ansible_distribution_release != "stretch" or mail.backend != "ssmtp")

tasks/nullmailer.yml

@@ -2,6 +2,16 @@
   apt:
     pkg: nullmailer
 
+- name: remove ssmtp
+  apt:
+    pkg: ssmtp
+    state: absent
+
+- name: remove ssmtp config
+  file:
+    path: /etc/ssmtp/ssmtp.conf
+    state: absent
+
 - name: setup nullmailer
   notify: restart nullmailer
   copy: