[horde] Default domain when using LDAP authentication

[Jason Voorhees]

Hi people:

I'm using Horde with LDAP authentication in a virtual domain
mailserver. Logins work without problems when users write their full
name (user at domain), and they access to their cyrus mailboxes (cyrus
with virtual domains support also) correctly.
But I would like to configure Horde to auto complete a default domain
to users who write their account without the @domain part.
These sentences I have in config/conf.php related to authentication

$conf['auth']['params']['uid'] = 'mail';
$conf['auth']['params']['filter'] =
'(&(objectClass=VirtualMailAccount)(accountActive=TRUE)(forwardActive=FALS
E))';
$conf['auth']['params']['filter_type'] = 'free';
$conf['auth']['driver'] = 'ldap';
$conf['auth']['params']['hostspec'] = 'localhost';
$conf['auth']['params']['basedn'] = 'o=hosting,dc=domain,dc=com,dc=pe';
$conf['auth']['params']['binddn'] = 'cn=phamm,o=hosting,dc=domain,dc=com,dc=pe';
$conf['auth']['params']['password'] = 'secret';

Users in my LDAP server are in the form:

'mail=user at domain.com,vd=domain.com,o=hosting,dc=domain,dc=com,dc=pe'.

I can see that LDAP (so then Horde) denies access to users without the
@domain part because there isn't any account of the form:

'mail=user,vd=domain.com,o=hosting,dc=domain,dc=com,dc=pe'   (mail is not FQDN)

So, setting could I do to autocomplete a default domain to no FQDN
users logins? I took a look at username_hook* in conf/hooks.php but
they're based on the URL contained in HTTP_POST.
I just want something more simple, a custom hook to complete
@domain.com.pe when it isn't present at the login username...
Do I need to use a custom hook to achieve this? If yes could somebody
help me a bit with some PHP code to detect->autocomplete a domain
part? I don't know anything about programming :(

Thanks, bye