[Exim] mailing lists with LDAP mailgroups

I try to proceed mailing-lists with exim.
these mailing-lists are defined in an LDAP directory.
the form is :
    dn: 'dn of the mailing list'
        objectclass: groupofnames
        objectclass: mailgroup
        mail: tous@domain (the mail address of the mailing)
        member: uid=algayon,ou=personnel,o=domain,dc=annuaire  (the DN
of the first member)
        member: .... (DN of the 2nd member)
        member: ....
        .....

I think it could be done with an aliasfile director.
this director would take in entry the address of the mailig list
(tous@domain) and would
give the list of the mail addresses of all the member of this list.

with an LDAP query, i find the list of the DNs of all the member of the
list, separated by a white space.
(with the query
ldap://server:389/'baseDN'?member?sub?(mail=tous@domain))

I now have to make an LDAP query to find the mail address of each these
DNs.

Does someone know if there is an easy way to do this.

thank you