[imp] Inbox is shown empty but it contains emails

[Anders Tietze]

Hi,

I have just upgrade from an old horde-3 installation to the latest  
horde groupware 5.0.4 but now I am experiencing some problems with IMP  
and the IMAP connection.

The IMAP server is a courier-imap and is working perfectly with the  
old horde installation.

And now to the problem.

When I access my inbox, no emails are displayed, which is wrong, it  
contain emails (checked by using an imap connection via mozilla  
thunderbird). My inbox also contains some subfolders e.g "Sent" which  
IMP is able to display the content of, but some other subfolders are  
shown empty which is also wrong.

 From the syslog i see the following error:
HORDE: [imp] Mail server closed the connection unexpectedly. [pid  
29325 on line 387 of "/XXX/imp/lib/Imap.php"]

and sometime
HORDE: [imp] Mail server closed the connection unexpectedly. [pid  
18481 on line 387 of "/XXX/imp/lib/Imap.php"]
HORDE: [imp] PHP ERROR: stream_get_contents() expects parameter 2 to  
be long, string given [pid 19706 on line 279 of  
"/usr/share/php/Horde/Imap/Client/Tokenize.php"]

If I the the horde/test.php ->imp part the imap test returns
"Bad tagged response."

The courier-imapd has the following capabilities configures:

IMAP_CAPABILITY="IMAP4rev1 CHILDREN NAMESPACE"

I have tried to google the errors but I can not find any suggestions  
that solves my issue.

Is there any debug I can enable in Horde or in the courier-imapd to  
get more clues of what is wrong?

Best regards,
Anders Tietze