diff --git a/roles/docker/defaults/main.yml b/roles/docker/defaults/main.yml
index 2d2a04e..9cf9cc4 100644
--- a/roles/docker/defaults/main.yml
+++ b/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 }}"
diff --git a/roles/docker/tasks/services/postfix.yml b/roles/docker/tasks/services/postfix.yml
index 70f5e5d..2851b71 100644
--- a/roles/docker/tasks/services/postfix.yml
+++ b/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