In order to use LDAP lookups, define an LDAP source
as a table lookup in main.cf, for example:
alias_maps = hash:/etc/aliases,
ldap:/etc/postfix/ldap-aliases.cf
The file /etc/postfix/ldap-aliases.cf can specify a great number
of parameters, including parameters that enable LDAP SSL and
STARTTLS. For a complete description, see the
ldap_table(5) manual
page.
