diff --git a/admin/mailu/admin/views/alternatives.py b/admin/mailu/admin/views/alternatives.py
index b3b4ab3b..ce237d45 100644
--- a/admin/mailu/admin/views/alternatives.py
+++ b/admin/mailu/admin/views/alternatives.py
@@ -19,7 +19,8 @@ def alternative_create(domain_name):
     if form.validate_on_submit():
         conflicting_domain = models.Domain.query.get(form.name.data)
         conflicting_alternative = models.Alternative.query.get(form.name.data)
-        if conflicting_domain or conflicting_alternative:
+        conflicting_relay = models.Relay.query.get(form.name.data)
+        if conflicting_domain or conflicting_alternative or conflicting_relay:
             flask.flash('Domain %s is already used' % form.name.data, 'error')
         else:
             alternative = models.Alternative(domain=domain)
diff --git a/admin/mailu/admin/views/domains.py b/admin/mailu/admin/views/domains.py
index 371b46f9..cebe5c8b 100644
--- a/admin/mailu/admin/views/domains.py
+++ b/admin/mailu/admin/views/domains.py
@@ -18,7 +18,8 @@ def domain_create():
     if form.validate_on_submit():
         conflicting_domain = models.Domain.query.get(form.name.data)
         conflicting_alternative = models.Alternative.query.get(form.name.data)
-        if conflicting_domain or conflicting_alternative:
+        conflicting_relay = models.Relay.query.get(form.name.data)
+        if conflicting_domain or conflicting_alternative or conflicting_relay:
             flask.flash('Domain %s is already used' % form.name.data, 'error')
         else:
             domain = models.Domain()