diff --git a/roles/docker/defaults/main.yml b/roles/docker/defaults/main.yml
index 2a23950..2acddce 100644
--- a/roles/docker/defaults/main.yml
+++ b/roles/docker/defaults/main.yml
@@ -6,6 +6,7 @@ services:
   ### Internal services ###
   postfix:
     file: postfix.yml
+    domain: "smtp.{{ base_domain }}"
     version: "v3.5.0"
 
   nginx_proxy:
diff --git a/roles/docker/tasks/services/postfix.yml b/roles/docker/tasks/services/postfix.yml
index 77dc727..1fb67df 100644
--- a/roles/docker/tasks/services/postfix.yml
+++ b/roles/docker/tasks/services/postfix.yml
@@ -17,4 +17,4 @@
     env:
       # Get all services which have allowed_sender_domain defined
       ALLOWED_SENDER_DOMAINS: "{{ services | dict2items | selectattr('value.allowed_sender_domain', 'true') | map(attribute='value.domain') | join(' ') }}"
-      HOSTNAME: "smtp.{{ base_domain }}" # the name the smtp server will identify itself as
+      HOSTNAME: "{{ services.postfix.domain }}" # the name the smtp server will identify itself as