Fix issue #1455 (introduct in d261b1e89c3d4d5191036d5a5660ef6764e593a0)
diff --git a/system/libraries/Email.php b/system/libraries/Email.php
index c70144f..09f2175 100644
--- a/system/libraries/Email.php
+++ b/system/libraries/Email.php
@@ -1599,7 +1599,7 @@
 
 		$this->_debug_msg[] = '<pre>'.$cmd.': '.$reply.'</pre>';
 
-		if (substr($reply, 0, 3) !== $resp)
+		if ( (int) substr($reply, 0, 3) !== $resp)
 		{
 			$this->_set_error_message('lang:email_smtp_error', $reply);
 			return FALSE;