[horde] Missing LDAP options

[neys]

Hello list,

since... actually I do no longer know since when, I guess when I 
switched from Horde 4 to Horde Webmail 5.x, I do have a problem with 
authentication via LDAP. The following error occours from imp, turba, 
nag, usw

> 2013-06-04T02:16:03+02:00 EMERG: HORDE [imp] Bad search filter
> Parameters:
> Base: o=bsdfocus.de
> Filter: (&(objectclass=)(=user at example.com))
> Scope: sub [pid 5067 on line 395 of "/usr/share/php/Horde/Group/Ldap.php"]

The interesting parts of my horde conf.php are:
> $conf['ldap']['hostspec'] = 'localhost';
> $conf['ldap']['tls'] = false;
> $conf['ldap']['version'] = 3;
> $conf['ldap']['binddn'] = 'uid=xxx,ou=xxx,ou=xxx,o=xxx';
> $conf['ldap']['bindpw'] = 'xxx';
> $conf['ldap']['bindas'] = 'admin';
> $conf['ldap']['useldap'] = true;
> $conf['auth']['params']['basedn'] = 'ou=yyy,ou=xxx,o=xxx';
> $conf['auth']['params']['scope'] = 'sub';
> $conf['auth']['params']['ad'] = false;
> $conf['auth']['params']['uid'] = 'mail';
> $conf['auth']['params']['encryption'] = 'ssha';
> $conf['auth']['params']['filter'] = '(&(objectclass=account)(objectclass=qmailUser))';
> $conf['auth']['params']['driverconfig'] = 'horde';
> $conf['auth']['driver'] = 'ldap';

Adding the following lines from my old Horde 4 conf.php solves the 
problem and everything is fine:
> $conf['ldap']['user']['uid'] = 'mail';
> $conf['ldap']['user']['objectclass'] = array('account', 'qmailUser');
> $conf['ldap']['user']['filter_type'] = 'objectclass';

I tried to take a look into the several hooks, but did not find anything 
useful.

Any ideas?

Neys