diff --git a/backend/multimail/forms.py b/backend/multimail/forms.py
index d51fbcf..b86efd0 100644
--- a/backend/multimail/forms.py
+++ b/backend/multimail/forms.py
@@ -109,6 +109,10 @@ def edit_mailbox(request, mailbox_id):
             if form.is_valid() and form.cleaned_data['domain'] in domains:
                 form.save()
                 return HttpResponseRedirect('/mailboxes/')
+            else:
+                if not form.cleaned_data['domain'] in domains:
+                    form.errors.clear()
+                    form.add_error(None, "You don't own this domain")
 
         except IntegrityError as e:
             form.add_error(None, e)
@@ -129,6 +133,10 @@ def new_mailbox(request):
             if form.is_valid() and form.cleaned_data['domain'] in domains:
                 form.save()
                 return HttpResponseRedirect('/mailboxes/')
+            else:
+                if not form.cleaned_data['domain'] in domains:
+                    form.errors.clear()
+                    form.add_error(None, "You don't own this domain")
 
         except IntegrityError as e:
             form.add_error(None, e)
@@ -153,6 +161,10 @@ def edit_alias(request, alias_id):
             if form.is_valid() and form.cleaned_data['source_domain'] in domains:
                 form.save()
                 return HttpResponseRedirect('/aliases/')
+            else:
+                if not form.cleaned_data['source_domain'] in domains:
+                    form.errors.clear()
+                    form.add_error(None, "You don't own this domain")
 
         except IntegrityError as e:
             form.add_error(None, e)
@@ -173,6 +185,10 @@ def new_alias(request):
             if form.is_valid() and form.cleaned_data['source_domain'] in domains:
                 form.save()
                 return HttpResponseRedirect('/aliases/')
+            else:
+                if not form.cleaned_data['source_domain'] in domains:
+                    form.errors.clear()
+                    form.add_error(None, "You don't own this domain")
 
         except IntegrityError as e:
             form.add_error(None, e)