diff --git a/attributs.py b/attributs.py
index 3948a7e..b6d24d0 100644
--- a/attributs.py
+++ b/attributs.py
@@ -480,7 +480,7 @@ class mail(Attr):
 @crans_attribute
 class canonicalAlias(mail):
     singlevalue = True
-    optional = False
+    optional = True
     unique = True
     legend = u"Alias mail canonique"
     category = 'mail'