MAILSERV LDAP schema MTA options

RESTRICTED. MAILSERV is not yet fully implemented.

There are a couple of MTA options specifying basics of the LDAP schema for MAILSERV.

See also:
 * ldap_mlsub_object_class MTA Option
 * ldap_mluser_basedn MTA Option
 * ldap_mluser_object_class MTA Option
 * MAILSERV MTA options
 * MTA options