From 064a96ec075d8a438af259f9095b89d39ce3567e Mon Sep 17 00:00:00 2001
From: Marc Alexander <admin@m-a-styles.de>
Date: Mon, 27 Jun 2022 22:36:25 +0200
Subject: [PATCH] [ticket/16932] Ensure special characters are encoded for
 ASCII in emails

PHPBB3-16932
---
 phpBB/includes/functions_messenger.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/phpBB/includes/functions_messenger.php b/phpBB/includes/functions_messenger.php
index 770223100b..749a8798e3 100644
--- a/phpBB/includes/functions_messenger.php
+++ b/phpBB/includes/functions_messenger.php
@@ -1882,7 +1882,7 @@ function mail_encode($str, $eol = "\r\n")
 	{
 		$encoded_char = $is_quoted_printable
 			? $char = preg_replace_callback(
-				'/[=_\?\x20\x00-\x1F\x80-\xFF]/',
+				'/[()<>@,;:\\\\".\[\]=_?\x20\x00-\x1F\x80-\xFF]/',
 				function ($matches)
 				{
 					$hex = dechex(ord($matches[0]));