I have this json request in PHP:
===

        $req_data = array('jsonrpc' => '2.0',
                          'method'  => 'item.get',
                          'auth'    => $auth_data,
                          'params'  => array(
                              'groupids'    => [6, 7],
                              'selectHosts' => 'extend',
                              'output'      => 'extend',
                              'search'      => array(
                                  'key_' => "outgoing_emails"
                              ),
                          ),
                          'id'      => 2
        );

===
This key is a Zabbix trapper of type text which gets data every 7 days through zabbix_sender. Zabbix API runs this query (from mysql general_log):
===
SELECT * FROM history_text h WHERE h.itemid='207783' AND h.clock>1425309743 ORDER BY h.clock DESC LIMIT 2 OFFSET 0
===
where clock 1425309743 (Mon Mar 2 16:22:23 CET 2015)
is limited to the last 24 hours but the last value for this key was received on 27 Feb 2015, so as a result the API returns
===
lastclock: 0
lastvalue: 0
===

The current values of this item are:
===
select from_unixtime(clock), itemid, value from history_text where itemid=207783 order by clock desc;

1. from_unixtime(clock), clock, itemid, value
   '2015-02-27 10:54:14', '1425030854', '207783', '20204 124986 248'
   '2015-02-23 11:06:03', '1424685963', '207783', '19924 123672 246'
   '2015-02-20 10:54:38', '1424426078', '207783', '19942 125017 245'
   '2015-02-16 22:41:44', '1424122904', '207783', '20296 127645 243'
   '2015-02-16 21:29:52', '1424118592', '207783', '20254 127166 243'
   '2015-02-13 10:55:09', '1423821309', '207783', '20154 122326 243'
   ===