Direct LDAP attributes returned upon authentication MTA options

By default, the MTA and the authentication library assume a particular sort of LDAP schema. However, as of the 8.0 release the exact attribute names that the authentication library returns (for the MTA to use) are configurable via  various   MTA options.

See also:
 * ldap_auth_attr_mail_host MTA Option
 * ldap_auth_attr_sender MTA Option
 * ldap_auth_attr_submit_channel MTA Option
 * ldap_auth_attr_recall_secret MTA Option
 * ldap_auth_attr_hold_for MTA Option
 * Direct LDAP attribute name MTA options