This fix wont work. Users who have no additional folders are no able 
to log in. But existing folders wont be shown anymore.

I have the same problem with the current horde groupware edition. One 
of my users is complaining about this problem and I tried this patch. 
Now the user is able to log in. But if I log in to my account, I can 
only see my inbox, no additional folders. If I remove the patch, all 
folders are shown again.

Yes, its definitely a showstopper and it took me some hours today with 
a fresh Installation of horde webmail on a freshly set up mailserver 
until I found this bug report. First test-account worked (had more 
than .INBOX), second one didn't. That confused me a bit. Would you 
mind to release the patch ASAP, please? What about calling it 4.3.8.1 
if 4.3.9 isn't ready for release yet? Honestly thank you for your 
great work!! :)

Unfortunately, this is a showstopper and I will need to release 4.3.9 
soon.  Stupid undefined array.

Changes have been made in CVS for this ticket:

Bug: 9273
changelog
http://cvs.horde.org/diff.php/imp/docs/CHANGES?rt=horder1=1.699.2.431r2=1.699.2.432ty=u

Removed our hack and implemented diff patch at 
http://git.horde.org/diff.php/imp/lib/IMAP/Tree.php?rt=horde&r1=1.25.2.72&r2=1.25.2.73 which declares/initializes $names as an array prior to referencing it.  This addresses the issue we were 
seeing.

Thanks.

Can you try this patch instead?  Your patch isn't correct because it 
assumes that if INBOX doesn't exist, no other mailboxes exist.  It is 
entirely possible that an IMAP server returns a bunch of folder names 
*except* INBOX (this is the exact reason for the change between 4.3.7 
and 4.3.8).  The use of the addition operator ensures that the Inbox 
always appears first in the list.

Changes have been made in CVS for this ticket:

Bug: 9273
$names might not be an array here.
http://cvs.horde.org/diff.php/imp/lib/IMAP/Tree.php?rt=horder1=1.25.2.72r2=1.25.2.73ty=u

Some of our users complained about receiving this error right after we 
upgraded to IMP 4.3.8:

Fatal error: Unsupported operand types in 
/home/web/appversions/horde-3.3.9/imp-h3-4.3.8/lib/IMAP/Tree.php on 
line 333

We isolated the complaining users as those with only INBOX mailbox and 
no other IMAP mailboxes in their Maildir store on the server.

When we patch lib/IMAP/Tree.php as follows, the error does not occur 
and these users are able to use IMP.  However, this patch has not been 
thoroughly tested.

--- Tree.php.1  2010-09-11 11:59:11.000000000 -0500
+++ Tree.php    2010-09-29 11:38:25.000000000 -0500
@@ -330,7 +330,8 @@

          if (!isset($names['INBOX'])) {
              /* INBOX must always appear. */
-            $names = array('INBOX' => 1) + $names;
+            /*$names = array('INBOX' => 1) + $names;*/
+            $names = array('INBOX' => 1);
          }

          if ($showunsub) {

From diff'ing lib/IMAP/Tree.php, it appears this bug was introduced 
during the change from IMP 4.3.7 to 4.3.8.

We use Courier IMAP 4.1.3 as our POP/IMAP server.

We are running IMP with Horde RHEL5.x using PHP 5.2.x, and our IMP 
config/servers.php is configured as follows:

$servers['imap'] = array(
     'name' => 'Imap server',
     'server' => 'imap-server-hostname.XXXX.YYY',
     'hordeauth' => false,
     'protocol' => 'imap/ssl/novalidate-cert',
     'port' => 993,
     'maildomain' => 'XXXX.YYY',
     'smtphost' => 'smtp-server-hostname.XXXX.YYY',
     'smtpport' => 25,
     'realm' => '',
     'preferred' => '',
);