Remove ssmtp support and add From overwrite option

defaults/main.yml

@@ -1,5 +1,8 @@
 mail:
+  from: "noreply@example.com"
+  overwrite_from_envelope: no
+  overwrite_from_header: no
+  overwrite_from_header_except_users: []
   root: "root@example.com"
   server: "mail.example.com"
   domain: "example.com"
-  backend: nullmailer