diff --git a/modoboa/extensions/admin/models/domain_alias.py b/modoboa/extensions/admin/models/domain_alias.py
index 382ba74e3..a24549b96 100644
--- a/modoboa/extensions/admin/models/domain_alias.py
+++ b/modoboa/extensions/admin/models/domain_alias.py
@@ -1,7 +1,7 @@
 import reversion
 from django.db import models
 from django.utils.translation import ugettext as _, ugettext_lazy
-from modoboa.lib.exceptions import BadRequest
+from modoboa.lib.exceptions import BadRequest, Conflict
 from .base import AdminObject
 from .domain import Domain
 
@@ -38,6 +38,12 @@ class DomainAlias(AdminObject):
         if len(row) < 4:
             raise BadRequest(_("Invalid line"))
         self.name = row[1].strip()
+        try:
+            Domain.objects.get(name=self.name)
+        except Domain.DoesNotExist:
+            pass
+        else:
+            raise Conflict(_("A domain %s already exists" % self.name))
         domname = row[2].strip()
         try:
             self.target = Domain.objects.get(name=domname)
diff --git a/modoboa/extensions/admin/tests/import_.py b/modoboa/extensions/admin/tests/import_.py
index 186f3ff1d..89ffdffdd 100644
--- a/modoboa/extensions/admin/tests/import_.py
+++ b/modoboa/extensions/admin/tests/import_.py
@@ -40,6 +40,17 @@ domainalias; domalias1.com; domain1.com; True
         self.assertFalse(dom.enabled)
         self.assertTrue(admin.is_owner(dom))
 
+    def test_import_domains_with_conflict(self):
+        f = ContentFile(b"""domain;test.alias;10;True
+domainalias;test.alias;test.com;True
+""", name="domains.csv")
+        resp = self.clt.post(
+            reverse("modoboa.extensions.admin.views.import.import_domains"), {
+                "sourcefile": f
+            }
+        )
+        self.assertIn('A domain test.alias already exists', resp.content)
+
     def test_identities_import(self):
         f = ContentFile(b"""
 account; user1@test.com; toto; User; One; True; SimpleUsers; user1@test.com