[exim] smtp auth with users in ldap and different 'ou'

Hi,

I have setup my authenticator like that from the exim wiki

 plain_server:
   driver = plaintext
   server_advertise_condition = ${if 
match{$sender_host_address}{\N^10\.0\.0\.\d{1,3}\N}{0}{1}}
   public_name = PLAIN
   server_condition = ${if ldapauth \
    {user="uid=${quote_ldap_dn:$2},ou=people,o=mydomain.com" \
    pass=${quote:$3} \
    ldap://LDAPSERVER:389/}{yes}{no}}
   server_set_id = $2
   server_prompts = :

all is working fine until my users are under ou=people

what solution can I use to authenticate users not under ou=people ?

thanks in advance.

Patrice