From 7fe57f275eb808c237b33fb2750c0aec40fd3079 Mon Sep 17 00:00:00 2001
From: Aleksander Machniak <alec@alec.pl>
Date: Wed, 18 Oct 2023 19:36:43 +0200
Subject: [PATCH] Fix duplicated Inbox folder on IMAP servers that do not use
 Inbox folder with all capital letters (#9166)

---
 CHANGELOG.md                                 |  1 +
 program/lib/Roundcube/rcube_imap_generic.php | 12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index bd03ea0e102..b8155f0761b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## Unreleased
 
 - Fix PHP8 fatal error when parsing a malformed BODYSTRUCTURE (#9171)
+- Fix duplicated Inbox folder on IMAP servers that do not use Inbox folder with all capital letters (#9166)
 
 ## Release 1.6.4
 
diff --git a/program/lib/Roundcube/rcube_imap_generic.php b/program/lib/Roundcube/rcube_imap_generic.php
index 83d4ad0ad2c..afe7c23c7af 100644
--- a/program/lib/Roundcube/rcube_imap_generic.php
+++ b/program/lib/Roundcube/rcube_imap_generic.php
@@ -1650,6 +1650,18 @@ protected function _listMailboxes($ref, $mailbox, $subscribed = false, $return_o
                         $mailbox = rtrim($mailbox, $delim);
                     }
 
+                    // Make it easier for the client to deal with INBOX folder
+                    // by always returning the word with all capital letters
+                    if (strlen($mailbox) == 5
+                        && ($mailbox[0] == 'i' || $mailbox[0] == 'I')
+                        && ($mailbox[1] == 'n' || $mailbox[1] == 'N')
+                        && ($mailbox[2] == 'b' || $mailbox[2] == 'B')
+                        && ($mailbox[3] == 'o' || $mailbox[3] == 'O')
+                        && ($mailbox[4] == 'x' || $mailbox[4] == 'X')
+                    ) {
+                        $mailbox = 'INBOX';
+                    }
+
                     // Add to result array
                     if (!$lstatus) {
                         $folders[] = $mailbox;