diff --git a/wp-includes/functions-formatting.php b/wp-includes/functions-formatting.php
index a0270e47a..9237feba4 100644
--- a/wp-includes/functions-formatting.php
+++ b/wp-includes/functions-formatting.php
@@ -305,7 +305,7 @@ function convert_smilies($text) {
 
 
 function is_email($user_email) {
-	$chars = "/^([a-z0-9_]|\\-|\\.)+@(([a-z0-9_]|\\-)+\\.)+[a-z]{2,4}\$/i";
+	$chars = "/^([a-z0-9+_]|\\-|\\.)+@(([a-z0-9_]|\\-)+\\.)+[a-z]{2,6}\$/i";
 	if(strstr($user_email, '@') && strstr($user_email, '.')) {
 		if (preg_match($chars, $user_email)) {
 			return true;