diff --git a/defaults/main.yml b/defaults/main.yml
index fd90004..3713d7b 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -2,3 +2,4 @@ mail:
   root: "root@example.com"
   server: "mail.example.com"
   domain: "example.com"
+  backend: nullmailer
diff --git a/tasks/main.yml b/tasks/main.yml
index a781495..3f9d183 100644
--- a/tasks/main.yml
+++ b/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")
diff --git a/tasks/nullmailer.yml b/tasks/nullmailer.yml
index 70c0554..2a73047 100644
--- a/tasks/nullmailer.yml
+++ b/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: