Fix bug where sent message was saved in Sent folder even if disabled by user (#1490208)

CHANGELOG

@@ -15,6 +15,7 @@ CHANGELOG Roundcube Webmail
 - Fix some rcube_utils::anytodatetime() corner cases with timezone mismatches (#1490163)
 - Improve move-to and contact-export button in classic skin (#1490166)
 - Fix wrong icon for download button in classic skin
+- Fix bug where sent message was saved in Sent folder even if disabled by user (#1490208)
 
 RELEASE 1.1-beta
 ----------------

program/steps/mail/sendmail.inc

@@ -564,8 +564,10 @@ if ($savedraft) {
     $store_target = $drafts_mbox;
 }
 else if (!$RCMAIL->config->get('no_save_sent_messages')) {
-    $store_target = rcube_utils::get_input_value('_store_target', rcube_utils::INPUT_POST);
-    if (!strlen($store_target)) {
+    if (isset($_POST['_store_target'])) {
+        $store_target = rcube_utils::get_input_value('_store_target', rcube_utils::INPUT_POST);
+    }
+    else {
         $store_target = $RCMAIL->config->get('sent_mbox');
     }
 }