Refactor allowed_sender_domains and allow more

A new object 'postfix' is created with a list of allowed_sender_domains.
Any services that expect to send mail this way should add its sender
domain to that list.

roles/docker/defaults/main.yml

@@ -98,3 +98,9 @@ ttrss:
 keycloak:
   domain: sso.{{ base_domain }}
   volume_folder: "{{ volume_root_folder }}/keycloak"
+
+postfix:
+  allowed_sender_domains:
+  - "services.{{ base_domain }}"
+  - "{{ passit.domain }}"
+  - "{{ fider.domain }}"

roles/docker/tasks/services/postfix.yml

@@ -15,5 +15,6 @@
     networks:
       - name: postfix
     env:
-      ALLOWED_SENDER_DOMAINS: "services.{{ base_domain }}"
+      ALLOWED_SENDER_DOMAINS: "{{ postfix.allowed_sender_domains|join(' ') }}"
+      HOSTNAME: "mail.data.coop" # the name the smtp server will identify itself as