If the PMDF options LDAP_HOST, LDAP_PORT, and REVERSE_URL are specified in the PMDF option file (see Section 7.3.2 ), then each address passing through PMDF will be checked against the LDAP server specified by the LDAP_HOST and LDAP_PORT options, using the LDAP query specified by the REVERSE_URL option. If the LDAP query succeeds and returns a value, that value will be substituted in place of the original address.
For the REVERSE_URL option, standard LDAP URLs must be used, except with the host and port omitted, as the host and port are instead specified via the LDAP_HOST and LDAP_PORT PMDF options. That is, the LDAP URL should be specified as
ldap:///dn[?attributes[?scope?filter]]where the square bracket characters
[ and
] shown above indicate optional portions of the
URL. The dn is required and is a distinguished
name specifying the search base; it might correspond to the
organization's top level in the Directory Information Tree, or it might
correspond to a subset of the organization, based upon the domain name
in the original address. The optional attributes,
scope, and filter portions
of the URL further refine what information to return. For address
reversal, the desired attributes to specify
returning would typically be the mail attribute (or some
similar attribute). The scope may be any of
base (the default), one, or sub.
And the desired filter would typically be based
upon the mailbox (local portion) of the incoming addresses. Certain
substitution sequences may be used to construct the LDAP search URL;
see Table 3-1 for details.