diff --git a/CRM/Contact/BAO/Query.php b/CRM/Contact/BAO/Query.php
index 4fc9bd6f213c..b4c5951fb6e2 100644
--- a/CRM/Contact/BAO/Query.php
+++ b/CRM/Contact/BAO/Query.php
@@ -4703,11 +4703,11 @@ public static function appendAnyValueToSelect($selectClauses, $groupBy) {
    *
    */
   public static function getGroupByFromOrderBy(&$groupBy, $orderBys) {
-    if (!CRM_Utils_SQL::disableFullGroupByMode()) {
+    if (CRM_Utils_SQL::disableFullGroupByMode()) {
       foreach ($orderBys as $orderBy) {
         $orderBy = str_replace(array(' DESC', ' ASC'), '', $orderBy); // remove sort syntax from ORDER BY clauses if present
         // if ORDER BY column is not present in GROUP BY then append it to end
-        if (!strstr($groupBy, $orderBy)) {
+        if (preg_match('/(MAX|MIN)\(/i', trim($orderBy)) !== 1 && !strstr($groupBy, $orderBy)) {
           $groupBy .= ", {$orderBy}";
         }
       }
diff --git a/CRM/Report/Form/Mailing/Summary.php b/CRM/Report/Form/Mailing/Summary.php
index 75f2b9617478..3d41981a6e80 100644
--- a/CRM/Report/Form/Mailing/Summary.php
+++ b/CRM/Report/Form/Mailing/Summary.php
@@ -149,11 +149,13 @@ public function __construct() {
       'order_bys' => array(
         'start_date' => array(
           'title' => ts('Start Date'),
+          'dbAlias' => 'MAX(mailing_job_civireport.start_date)',
         ),
         'end_date' => array(
           'title' => ts('End Date'),
           'default_weight' => '1',
           'default_order' => 'DESC',
+          'dbAlias' => 'MAX(mailing_job_civireport.end_date)',
         ),
       ),
       'grouping' => 'mailing-fields',