From a4de40566deddbedf0b7eba00e7665a8723bc9b2 Mon Sep 17 00:00:00 2001
From: Aleksander Machniak <alec@alec.pl>
Date: Tue, 16 Jan 2018 16:17:16 +0100
Subject: [PATCH] Validate ACL identifiers

... e.g. to prevent cyrus imap issues
---
 plugins/acl/acl.php | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/plugins/acl/acl.php b/plugins/acl/acl.php
index 31cb514f6..9a015956d 100644
--- a/plugins/acl/acl.php
+++ b/plugins/acl/acl.php
@@ -494,6 +494,13 @@ class acl extends rcube_plugin
                 if (!strpos($user, '@') && ($realm = $this->get_realm())) {
                     $user .= '@' . rcube_utils::idn_to_ascii(preg_replace('/^@/', '', $realm));
                 }
+
+                // Make sure it's valid email address to prevent from "disappearing folder"
+                // issue in Cyrus IMAP e.g. when the acl user identifier contains spaces inside.
+                if (strpos($user, '@') && !rcube_utils::check_email($user, false)) {
+                    $user = null;
+                }
+
                 $username = $user;
             }