diff --git a/modoboa/imap_migration/api/v2/serializers.py b/modoboa/imap_migration/api/v2/serializers.py
index 0af2ae3df..213898637 100644
--- a/modoboa/imap_migration/api/v2/serializers.py
+++ b/modoboa/imap_migration/api/v2/serializers.py
@@ -35,6 +35,7 @@ class EmailProviderDomainSerializer(serializers.ModelSerializer):
     id = serializers.IntegerField(required=False)
 
     class Meta:
+        extra_kwargs = {"name": {"validators": []}}
         fields = ("id", "name", "new_domain")
         model = models.EmailProviderDomain
 
@@ -56,6 +57,19 @@ class EmailProviderSerializer(serializers.ModelSerializer):
         if domains:
             to_create = []
             for domain in domains:
+                if models.EmailProviderDomain.objects.filter(
+                    name=domain["name"]
+                ).exists():
+                    raise serializers.ValidationError(
+                        {
+                            "error": (
+                                _("Migrated domain with name {} already exists").format(
+                                    domain["name"]
+                                )
+                            )
+                        }
+                    )
+
                 to_create.append(
                     models.EmailProviderDomain(provider=provider, **domain)
                 )
diff --git a/modoboa/imap_migration/tests.py b/modoboa/imap_migration/tests.py
index a972f2927..0841a091b 100644
--- a/modoboa/imap_migration/tests.py
+++ b/modoboa/imap_migration/tests.py
@@ -134,6 +134,13 @@ class ViewSetTestCase(DataMixin, ModoAPITestCase):
             models.EmailProviderDomain.objects.filter(name="gmail.com").exists()
         )
 
+        response = self.client.post(url, data, format="json")
+        self.assertEqual(response.status_code, 400)
+        self.assertEqual(
+            response.json()["error"],
+            "Migrated domain with name gmail.com already exists",
+        )
+
     def test_update_provider(self):
         provider_domain = factories.EmailProviderDomainFactory(name="outlook.com")
         url = reverse("v2:emailprovider-detail", args=[provider_domain.provider.pk])