diff --git a/modoboa/admin/api/v2/serializers.py b/modoboa/admin/api/v2/serializers.py
index 98af9b13d..9c2d77829 100644
--- a/modoboa/admin/api/v2/serializers.py
+++ b/modoboa/admin/api/v2/serializers.py
@@ -356,12 +356,14 @@ class WritableAccountSerializer(v1_serializers.WritableAccountSerializer):
             instance.set_password(password)
         if mailbox_data:
             creator = self.context["request"].user
-            if instance.mailbox:
+            if hasattr(instance, "mailbox"):
                 if "username" in validated_data:
                     mailbox_data["email"] = validated_data["username"]
                     instance.email = validated_data["username"]
                 instance.mailbox.update_from_dict(creator, mailbox_data)
-            else:
+            elif "username" in validated_data:
+                mailbox_data["full_address"] = validated_data["username"]
+                instance.email = validated_data["username"]
                 self._create_mailbox(creator, instance, mailbox_data)
         instance.save()
         self.set_permissions(instance, domains)
diff --git a/modoboa/admin/api/v2/tests.py b/modoboa/admin/api/v2/tests.py
index 4705f117d..09b83a756 100644
--- a/modoboa/admin/api/v2/tests.py
+++ b/modoboa/admin/api/v2/tests.py
@@ -158,6 +158,38 @@ class AccountViewSetTestCase(ModoAPITestCase):
         with self.assertRaises(core_models.User.DoesNotExist):
             account.refresh_from_db()
 
+    def test_update(self):
+        account = core_models.User.objects.get(username="user@test.com")
+        url = reverse("v2:account-detail", args=[account.pk])
+        data = {
+            "username": "user@test.com",
+            "role": "SimpleUsers",
+            "password": "Toto12345",
+            "mailbox": {
+                "quota": 10
+            }
+        }
+        resp = self.client.patch(url, data, format="json")
+        self.assertEqual(resp.status_code, 200)
+
+    def test_update_admin(self):
+        account = core_models.User.objects.get(username="admin")
+        url = reverse("v2:account-detail", args=[account.pk])
+        data = {
+            "username": "superadmin@test.com",
+            "role": "SuperAdmins",
+            "password": "Toto12345",
+            "mailbox": {
+                "quota": 10
+            }
+        }
+        resp = self.client.patch(url, data, format="json")
+        self.assertEqual(resp.status_code, 200)
+
+        account.refresh_from_db()
+        self.assertEqual(account.email, data["username"])
+        self.assertEqual(account.mailbox.full_address, data["username"])
+
 
 class IdentityViewSetTestCase(ModoAPITestCase):
 
@@ -235,6 +267,10 @@ class UserAccountViewSetTestCase(ModoAPITestCase):
             2
         )
 
+        resp = self.client.get(url)
+        self.assertEqual(resp.status_code, 200)
+        self.assertTrue(resp.json()["keepcopies"])
+
         data = {"keepcopies": False}
         resp = self.client.post(url, data, format="json")
         self.assertEqual(resp.status_code, 200)