IMAP account setup fails on servers returning root "" mailbox and incomplete ACL support (e.g. Xserver) #12367
Description
Steps to reproduce
When adding an IMAP account in Nextcloud Mail, account setup fails on some IMAP servers
(e.g. Xserver, common in Japan).
The failure happens during folder initialization / STATUS fetching.
Expected behavior
- Root placeholder / empty mailboxes should be ignored for STATUS
- STATUS should be fetched per mailbox with error isolation
- ACL capability should be treated defensively
Actual behavior
- IMAP LIST/LSUB returns a root placeholder mailbox
""(NOSELECT) - Nextcloud Mail attempts to call STATUS on it
- Server returns NO / BAD
- This aborts account setup
Additionally:
- Server advertises
CAPABILITY ACL - But
GETMYRIGHTS/ ACL-related commands are not fully implemented - This causes further failures during folder ACL fetch
Mail app version
5.7.0-rc.1
Nextcloud version
32.0.5
Mailserver or service
Xserver
Operating system
Ubuntu24.04.2live server
PHP engine version
PHP 8.3
Nextcloud memory caching
No response
Web server
None
Database
None
Additional info
The modification of FolderMapper.php can fix this issue.