diff --git a/addons/mail/res_config.py b/addons/mail/res_config.py
index 91606e1c720..0e2e362d07b 100644
--- a/addons/mail/res_config.py
+++ b/addons/mail/res_config.py
@@ -33,14 +33,14 @@ class project_configuration(osv.TransientModel):
     }
 
     def get_default_alias_domain(self, cr, uid, ids, context=None):
-        alias_domain = self.pool.get("ir.config_parameter").get_param(cr, uid, "mail.catchall.domain", context=context)
-        if not alias_domain:
+        alias_domain = self.pool.get("ir.config_parameter").get_param(cr, uid, "mail.catchall.domain", default=None, context=context)
+        if alias_domain is None:
             domain = self.pool.get("ir.config_parameter").get_param(cr, uid, "web.base.url", context=context)
             try:
                 alias_domain = urlparse.urlsplit(domain).netloc.split(':')[0]
             except Exception:
                 pass
-        return {'alias_domain': alias_domain}
+        return {'alias_domain': alias_domain or False}
 
     def set_alias_domain(self, cr, uid, ids, context=None):
         config_parameters = self.pool.get("ir.config_parameter")