diff --git a/core/asynctask.class.inc.php b/core/asynctask.class.inc.php
index 6d8ad04d3..656229bf3 100644
--- a/core/asynctask.class.inc.php
+++ b/core/asynctask.class.inc.php
@@ -140,7 +140,7 @@ class AsyncSendEmail extends AsyncTask
 		MetaModel::Init_InheritAttributes();
 
 		MetaModel::Init_AddAttribute(new AttributeInteger("version", array("allowed_values"=>null, "sql"=>"version", "default_value"=>Email::ORIGINAL_FORMAT, "is_null_allowed"=>false, "depends_on"=>array())));
-		MetaModel::Init_AddAttribute(new AttributeText("to", array("allowed_values"=>null, "sql"=>"to", "default_value"=>null, "is_null_allowed"=>false, "depends_on"=>array())));
+		MetaModel::Init_AddAttribute(new AttributeText("to", array("allowed_values"=>null, "sql"=>"to", "default_value"=>null, "is_null_allowed"=>true, "depends_on"=>array())));
 		MetaModel::Init_AddAttribute(new AttributeText("subject", array("allowed_values"=>null, "sql"=>"subject", "default_value"=>null, "is_null_allowed"=>false, "depends_on"=>array())));
 		MetaModel::Init_AddAttribute(new AttributeLongText("message", array("allowed_values"=>null, "sql"=>"message", "default_value"=>null, "is_null_allowed"=>false, "depends_on"=>array())));