[Courier-imap] Problem about "Mailbox does not exist, or must be subscribed to" after version upgrade from 4.18.2 to 5.0.

[Neko C. <ep...@gm...>]

Hi courier-imap mail list.

I come from Taiwan, so please forgive my poor English.
I using courier-imap series 4 and work fine, but encounter problem after
upgrade to 5.0 (other courier relation package upgrade to latest version
also).
Detail error "The current operation on 'Inbox' did not succeed, The mail
server of account "sy...@ep... responded: Mailbox does not exist, or
must be subscribed to" show when subscribed folder selected in exist
account @ Thunderbird 60.0.2 in Ubuntu 16.04 LTS
And folder list empty when I tried to subscript folder.
Can help me?

I found similar list @
https://sourceforge.net/p/courier/mailman/message/32956742/ but it
different with my problem.
And checked http://www.courier-mta.org/imap/INSTALL.html#upgrading haven't
information about 5.0 upgrade.

Situation:
Server: FreeBSD 11.2-RELEASE amd64, hostname: epopen.com

Dependence Courier package version:
courier-authlib-base: 0.69.0
courier-authlib-mysql: 0.69.0
courier-unicode: 2.1

One imap account: sy...@ep..., created from Courier-imap version
series 4.
Maildir path: /home/vmail/epopen.com/system.
Maildir owner/group: vmail (uid/gid=50000).

Debug:
1. Current Maildir information.
drwx------  6 vmail  vmail      9 Nov  1 22:26 .Deleted Messages/
drwx------  6 vmail  vmail      9 Nov  2 09:39 .Drafts/
drwx------  6 vmail  vmail      9 Nov  6 10:06 .Junk/
drwx------  6 vmail  vmail      9 Oct 30 09:56 .Notes/
drwx------  6 vmail  vmail      9  Mar  7 14:33 .Sent/
drwx------  6 vmail  vmail      9 Oct 30 10:17 .Sent Messages/
drwx------  6 vmail  vmail      9 Nov  2 18:28 .Trash/
-rw-r--r--  1 vmail  vmail     43 Oct  5 11:43 courierimapacl
drwxr-xr-x  2 vmail  vmail      2 Oct  5 11:42 courierimaphieracl/
drwx------  2 vmail  vmail      2 Oct 29 21:21 courierimapkeywords/
-rw-r--r--  1 vmail  vmail    102 Nov  1 09:59 courierimapsubscribed
-rw-r--r--  1 vmail  vmail     20 Nov  6 09:34 courierimapuiddb
drwx------  2 vmail  vmail      2 Nov  6 09:34 cur/
drwx------  2 vmail  vmail      4 Nov  6 10:40 new/
drwx------  2 vmail  vmail      2 Nov  6 10:45 tmp/

2. Add DEBUG_LOGIN=2 into /usr/local/etc/authlib/authdaemonrc and get
result from maillog as below.
Nov  2 16:35:11 mail imapd: Connection, ip=[::ffff:60.251.70.131]
Nov  2 16:35:11 mail authdaemond: received auth request, service=imap,
authtype=login
Nov  2 16:35:11 mail authdaemond: authmysql: trying this module
Nov  2 16:35:11 mail authdaemond: SQL query: SELECT username, password, '',
'50000', '50000', '/home/vmail/' as home, maildir, concat(quota,'S'), name,
'' FROM mailbox WHERE username = 'sy...@ep...' AND (active='1')
Nov  2 16:35:11 mail authdaemond: password matches successfully
Nov  2 16:35:11 mail authdaemond: authmysql: sysusername=<null>,
sysuserid=50000, sysgroupid=50000, homedir=/home/vmail/, address=
sy...@ep..., fullname=For General, maildir=epopen.com/system/,
quota=0S, options=<null>
Nov  2 16:35:11 mail authdaemond: authmysql: clearpasswd=BARFOO,
passwd=$1$BARFOO.

3. Add IMAPDEBUGFILE=debug.dat into usr/local/etc/courier-imap/imapd &
impad-ssl and get result from debug.dat in maildir.
WRITE: 3 OK LOGIN Ok.
READ: NUMBER: 4
READ: ATOM: SELECT
READ: QUOTED_STRING: INBOX
WRITE: 4 NO Mailbox does not exist, or must be subscribed to.

4. Authentication test and test successful.
# authtest sy...@ep...
Authentication succeeded.

Authenticated: sy...@ep...  (uid 50000, gid 50000)
Home Directory: /home/vmail/
Maildir: epopen.com/system/
Quota: 0S
Encrypted Password: $1$BARFOO
Cleartext Password: (none)
Options: wbnodsn=1

5. if change whole maildir owner/grout by  'chown -R courier:courier
/home/vmail' cause much permission denied in maillog as below.
Nov  2 16:58:02 mail authdaemond: Authenticated: clearpasswd=BARFOO,
passwd=$1$BARFOO
Nov  2 16:58:02 mail imapd: chdir epopen.com/system/: Permission denied
Nov  2 16:58:02 mail imapd: sy...@ep...: Permission denied
Note: In the case, error from sub-directory because TOP directory
/home/vmail's owner:group roll-back to correct "vmail".

Addition, here I saw correct behavior about imapd get maildir information
from authdaemon and 'chdir' into it look like.

6. If change permission to world-wide read/write by 'chmod -R 777
/home/vmail'  (Note: user:group=vmail) problem exist.

I tried known debug method, but problem still.
Can teach me about other debug method?
Thanks a lot.

-- 
Regards,
Wei-Jen Chang