Instalación horde

["Sergio Villalba" <svillalba@cherrytel.com>]

Hola lista,

estoy intentando implementar el webmail horde, actualmente tengo el
squirrelmail pero quiero probar (debian+qmail+vpopmail+courier-imap). La
cosa es que se me esta atragantando por el siguiente error cuando
intento conectar:

Dec 14 16:27:41 web imapd: couriertls: connect: error:14094418:SSL
routines:SSL3_READ_BYTES:tlsv1 alert unknown ca
Dec 14 16:27:41 web imapd: Disconnected, ip=[::ffff:127.0.0.1], time=0,
starttls=1


horde/config/conf.php

$conf['use_ssl'] = 2;
$conf['server']['name'] = $_SERVER['SERVER_NAME'];
$conf['server']['port'] = $_SERVER['SERVER_PORT'];
$conf['cookie']['domain'] = $_SERVER['SERVER_NAME'];
$conf['cookie']['path'] = '/horde';

$conf['debug_level'] = "";
$conf['compress_pages'] = true;
$conf['session']['name'] = 'Horde';
$conf['session']['cache_limiter'] = 'nocache';
$conf['session']['timeout'] = 0;
$conf['auth']['admins'] = array('Administrator');
$conf['auth']['driver'] = 'imap';
$conf['auth']['params'] = array('username' => 'Administrator');
$conf['prefs']['driver'] = '';
$conf['css']['cached'] = false;
$conf['menu']['always'] = false;

horde/imp/config/servers.php

$servers['imap'] = array(
    'name' => 'IMAP Server',
    'server' => 'localhost',
    'hordeauth' => false,
    'protocol' => 'imap/notls',
    'port' => 143,
    'folders' => 'INBOX.',
    'namespace' => '',
    'maildomain' => 'horde.com',
    'smtphost' => 'localhost',
    'smtpport' => 25,
    'realm' => '',
    'preferred' => '',
    'dotfiles' => false,
    'hierarchies' => array()
);

Alguien me podria dar algunas pista.

Gracias por todo.
Un saludo.