Index: kernel/utility/email.php
===================================================================
--- kernel/utility/email.php	(revision 15230)
+++ kernel/utility/email.php	(working copy)
@@ -556,13 +556,13 @@
 	{
 		$add_recipient = Array ();
 
-		if ( array_key_exists('to_email', $this->params) ) {
+		if ( isset($this->params['to_email']) && $this->params['to_email'] ) {
 			$add_recipient['RecipientName'] = '';
 			$add_recipient['RecipientAddressType'] = EmailEvent::ADDRESS_TYPE_EMAIL;
 			$add_recipient['RecipientAddress'] = $this->params['to_email'];
 		}
 
-		if ( array_key_exists('to_name', $this->params) ) {
+		if ( isset($this->params['to_name']) && $this->params['to_name'] ) {
 			$add_recipient['RecipientName'] = $this->params['to_name'];
 		}