Smartsend use redis smartsend option

smartsend options:  (0 or 1)
The  smartsend option selects the backend database protocol used by the smartsend plugin. A value of 1 selects redis; a value of 0 selects memcache. The default if the option is not specified is to use redis if either the  or   option is set, memcache otherwise.

See also:
 * smartsend callouts
 * port Option
 * hostlist Option