Move matrix-email2matrix to its own container network

roles/custom/matrix-email2matrix/tasks/validate_config.yml

@@ -5,3 +5,13 @@
     msg: >
       You need to define at least one mapping in `matrix_email2matrix_matrix_mappings` for enabling Email2Matrix.
   when: "matrix_email2matrix_matrix_mappings | length == 0"
+
+- name: Fail if required email2matrix settings not defined
+  ansible.builtin.fail:
+    msg: >-
+      You need to define a required configuration setting (`{{ item.name }}`).
+  when: "item.when | bool and vars[item.name] == ''"
+  with_items:
+    - {'name': 'matrix_email2matrix_container_network', when: true}
+
+