diff --git a/modoboa/relaydomains/handlers.py b/modoboa/relaydomains/handlers.py
index 3c8d4d857..bd326199e 100644
--- a/modoboa/relaydomains/handlers.py
+++ b/modoboa/relaydomains/handlers.py
@@ -5,9 +5,11 @@ from django.dispatch import receiver
 
 from modoboa.admin import models as admin_models
 from modoboa.admin.signals import use_external_recipients
+from modoboa.core import signals as core_signals
 from modoboa.lib.email_utils import split_mailbox
 
 from . import models
+from . import postfix_maps
 
 
 @receiver(use_external_recipients)
@@ -39,3 +41,14 @@ def clean_domain(sender, instance, **kwargs):
         # at form level...
         models.RelayDomain.objects.create(
             domain=instance, service=models.Service.objects.first())
+
+
+@receiver(core_signals.register_postfix_maps)
+def register_postfix_maps(sender, **kwargs):
+    """Register postfix maps."""
+    return [
+        postfix_maps.RelayDomainsMap,
+        postfix_maps.RelayDomainsTransportMap,
+        postfix_maps.SplitedDomainsTransportMap,
+        postfix_maps.RelayRecipientVerification
+    ]
diff --git a/modoboa/relaydomains/postfix_maps.py b/modoboa/relaydomains/postfix_maps.py
index e38a9707f..1ca969379 100644
--- a/modoboa/relaydomains/postfix_maps.py
+++ b/modoboa/relaydomains/postfix_maps.py
@@ -1,7 +1,5 @@
 """Map file definitions for postfix."""
 
-from modoboa.core.commands.postfix_maps import registry
-
 
 class RelayDomainsMap(object):
 
@@ -116,9 +114,3 @@ class RelayRecipientVerification(object):
         "INNER JOIN admin_domain AS dom ON rdom.domain_id=dom.id "
         "WHERE rdom.verify_recipients=1 AND dom.name='%d'"
     )
-
-
-registry.add_files([
-    RelayDomainsMap, RelayDomainsTransportMap, SplitedDomainsTransportMap,
-    RelayRecipientVerification
-])