[exim] Expansion items map alternative for imbricate ldap lo…

Hello

I'm using LDAP back-end for my email users and groups.

In 6.10 we used this syntax to find groups members :

${map\
        {<, ${lookup ldapm{user=LDAP_EXIM_USER pass=LDAP_EXIM_PASS \
                ldap:///LDAP_BASE\
                ?member\
                ?sub\
                ?(&(mail=${local_part}@${domain})\
                (objectClass=a2l-groupOfNamesGidNumber)\
                (objectClass=zarafa-group))\
        }}}\
        {${lookup ldapm{user=LDAP_EXIM_USER pass=LDAP_EXIM_PASS \
                ldap:///LDAP_BASE\
                ?mail\
                ?sub\
                ?dn=${quote_ldap:$item}\
        }}}}

We are going to upgrade to 6.43 on CentOS 5 and map expansion is no
longer in exim.

What is the new solution to imbricate ldap queries ?

I take a look at this solution :
http://www.slideshare.net/jpmens/exim-and-ldap-1829032
but my ldap server is under 2.3 release and overlay member is unavailable.

Thanks for any help

Florent