diff -urp privatemsg/privatemsg.install privatemsg_new/privatemsg.install
--- privatemsg/privatemsg.install	2008-07-27 02:42:01.000000000 +0100
+++ privatemsg_new/privatemsg.install	2008-09-23 22:22:38.641200000 +0100
@@ -17,14 +17,8 @@ function privatemsg_schema() {
         'not null'      => TRUE,
         'unsigned'      => TRUE,
       ),
-      'recipient'     => array(
-        'description'   => t('UID of the recipient'),
-        'type'          => 'int',
-        'not null'      => TRUE,
-        'unsigned'      => TRUE,
-      ),
-      'author'     => array(
-        'description'   => t('UID of the author'),
+      'uid'     => array(
+        'description'   => t('UID of either the author or the recipient'),
         'type'          => 'int',
         'not null'      => TRUE,
         'unsigned'      => TRUE,
@@ -42,14 +36,21 @@ function privatemsg_schema() {
         'not null'      => TRUE,
         'unsigned'      => TRUE,
       ),
+      'deleted' => array(
+        'description'   => t('Whether the user has deleted this message'),
+        'type' => 'int',
+        'unsigned' => TRUE,
+        'not null' => TRUE,
+        'default' => 0
+      ),
+
     ),
     'indexes'         => array(
       '`mid`'               => array('`mid`'),
-      '`author`'            => array('`author`'),
       '`thread_id`'         => array('`thread_id`'),
-      '`recipient`'         => array('`recipient`'),
+      '`uid`'         => array('`uid`'),
       '`timestamp`'         => array('`timestamp`'),
-      '`new`'              => array('`mid`','`recipient`','`new`',),
+      '`new`'              => array('`mid`','`uid`','`new`',),
     ),
   );
   
diff -urp privatemsg/privatemsg.module privatemsg_new/privatemsg.module
--- privatemsg/privatemsg.module	2008-09-20 21:22:20.000000000 +0100
+++ privatemsg_new/privatemsg.module	2008-09-23 22:29:23.086800000 +0100
@@ -251,7 +251,7 @@ function privatemsg_list($uid = NULL) {
 
   $messages = array();
   while ($row = db_fetch_array($result)) {
-    $row['subject'] = l($row['subject'], 'messages/view/'. $row['id']);
+    $row['subject'] = l($row['subject'], 'messages/view/'. $row['thread_id']);
     $messages[] = $row;
   }
 
@@ -262,12 +262,6 @@ function privatemsg_list($uid = NULL) {
       switch ($index) {
         case 'id':
           continue 2;
-        case 'author':
-      	  $col = 'from';
-      	  break;
-        case 'recipient':
-          $col = 'to';
-          break;
         case 'timestamp':
           $col = arg(1) == 'sent' ? 'sent' : 'received';
           break;
@@ -362,7 +356,7 @@ function privatemsg_set_new_status($acco
     global $user;
     $account = $user;
   }
-  $query = "UPDATE {pm_index} pmi SET new = %d WHERE recipient = %d AND new = %d";
+  $query = "UPDATE {pm_index} pmi SET new = %d WHERE uid = %d AND new = %d";
   $arg[] = $new;
   $arg[] = $account->uid;
   $arg[] = ($new == 0) ? 1 : 0;
@@ -615,13 +609,15 @@ function pm_send($form, &$form_state) {
   }
   // 2) Save message to recipients.
   // Each recipient gets a record in the pm_index table.
-  $query = "INSERT INTO {pm_index} (mid, thread_id, recipient, author, timestamp, new) VALUES (%d, %d, %d, %d, %d, 1)";
+  $query = "INSERT INTO {pm_index} (mid, thread_id, uid, timestamp, new, deleted) VALUES (%d, %d, %d, %d, %d, 0)";
   foreach ($message['recipients'] as $recipient) {
     $mid = $message['mid'];
     $thread_id  = $message['thread_id'];
     $timestamp = $message['timestamp'];
-    db_query($query, $mid, $thread_id, $recipient->uid, $message['author']->uid , $timestamp);
+    db_query($query, $mid, $thread_id, $recipient->uid, $timestamp, 1);
   }
+  // Also add a record for tha author to the pm_index table - set  column "new" to 0.
+  db_query($query, $mid, $thread_id, $message['author']->uid , $timestamp, 0);
 
   drupal_set_message('A private message has been sent to '. $form_state['values']['recipient']);
 }
@@ -666,16 +662,12 @@ function pm_preview($form, &$form_state)
 function privatemsg_privatemsg_list_sent_alter(&$fragments, $account) {
   $fragments['primary_table'] = '{pm_message} pm';
 
-  $fragments['select'][]      = 'MAX(pm.mid) as id';
   $fragments['select'][]      = 'pmi.thread_id';
   $fragments['select'][]      = 'pm.subject';
-  if ($account->uid != $GLOBALS['user']->uid) {
-    $fragments['select'][] = 'pmi.author';
-  }
-  $fragments['select'][] = 'pmi.recipient';
   $fragments['select'][] = 'pmi.timestamp';
   $fragments['inner_join'][]  = 'INNER JOIN {pm_index} pmi ON pm.mid = pmi.mid';
-  $fragments['where'][]       = 'pmi.author = %d';
+  $fragments['where'][]       = 'pm.author = %d';
+  $fragments['where'][]       = 'pmi.deleted = 0';
   $fragments['group_by'][]  = 'pmi.thread_id';
   $order = 'MAX(pmi.timestamp)';
   $sort = 'desc';
@@ -684,13 +676,6 @@ function privatemsg_privatemsg_list_sent
       case ('subject'):
         $order = 'pm.subject';
         break;
-      case ('from'):
-        $order = 'pmi.author';
-        break;
-      case ('to'):
-        $order = 'pmi.recipient';
-        break;
-      case ('sent'):
       default:
         $order = 'pmi.timestamp';
     }
@@ -703,17 +688,13 @@ function privatemsg_privatemsg_list_sent
 function privatemsg_privatemsg_list_alter(&$fragments, $account) {
   $fragments['primary_table'] = '{pm_message} pm';
 
-  $fragments['select'][]      = 'MAX(pmi.mid) as id';
   $fragments['select'][]      = 'pmi.thread_id';
   $fragments['select'][]      = 'pm.subject';
-  $fragments['select'][]      = 'pmi.author';
-  if ($account->uid != $GLOBALS['user']->uid) {
-    $fragments['select'][] = 'pmi.recipient';
-  }
   $fragments['select'][] = 'pmi.timestamp';
   $fragments['select'][] = 'MAX(pmi.new) as new';
   $fragments['inner_join'][]  = 'INNER JOIN {pm_index} pmi ON pm.mid = pmi.mid';
-  $fragments['where'][]       = 'pmi.recipient = %d';
+  $fragments['where'][]       = 'pmi.uid = %d';
+  $fragments['where'][]       = 'pmi.deleted = 0';
   $fragments['group_by'][]  = 'pmi.thread_id';
   $order = 'pmi.new';
   $sort = 'desc';
@@ -722,13 +703,6 @@ function privatemsg_privatemsg_list_alte
       case ('subject'):
         $order = 'pm.subject';
         break;
-      case ('from'):
-        $order = 'pmi.author';
-        break;
-      case ('to'):
-        $order = 'pmi.recipient';
-        break;
-      case ('received'):
       default:
         $order = 'MAX(pmi.timestamp)';
     }
@@ -749,8 +723,7 @@ function privatemsg_privatemsg_load_alte
   $fragments['inner_join'][]  = 'INNER JOIN {pm_index} pmi ON pm.mid = pmi.mid';
   $fragments['where'][]       = 'pmi.mid = %d';
   $fragments['query_args'][]  = $pmid;
-  $fragments['where'][]       = 'pmi.recipient = %d or pmi.author = %d';
-  $fragments['query_args'][]  = $uid;
+  $fragments['where'][]       = 'pmi.uid = %d';
   $fragments['query_args'][]  = $uid;
 }
 
@@ -761,25 +734,18 @@ function privatemsg_privatemsg_messages_
   $fragments['where'][]       = 'pmi.thread_id = %d';
   $fragments['query_args'][]  = $thread_id;
   if (!(user_access('read all private messages'))) {
-    $fragments['where'][]       = 'pmi.author = %d';
-    $fragments['query_args'][]  = $uid;
-    $fragments['union_select'][]      = 'DISTINCT(pmi.mid) as mid';
-    $fragments['union_where'][]       = 'pmi.thread_id = %d';
-    $fragments['union_where'][]       = 'pmi.recipient = %d';
-    $fragments['query_args'][]  = $thread_id;
+    $fragments['where'][]       = 'pmi.uid = %d';
     $fragments['query_args'][]  = $uid;
   }
+  $fragments['where'][]       = 'pmi.deleted = 0';
   $fragments['order_by'][]  = 'mid ASC';
 }
 
 function privatemsg_privatemsg_participants_alter(&$fragments, $thread_id) {
   $fragments['primary_table'] = '{pm_index} pmi';
 
-  $fragments['select'][]      = 'pmi.recipient as uid';
+  $fragments['select'][]      = 'DISTINCT(pmi.uid) as uid';
   $fragments['where'][]       = 'pmi.thread_id = %d';
-  $fragments['union_select'][] = 'pmi.author as uid';
-  $fragments['union_where'][] = 'pmi.thread_id = %d';
-  $fragments['query_args'][]  = $thread_id;
   $fragments['query_args'][]  = $thread_id;
 }
 
@@ -787,9 +753,9 @@ function privatemsg_privatemsg_participa
 function privatemsg_privatemsg_unread_count_alter(&$fragments, $account) {
   $fragments['primary_table'] = '{pm_index} pmi';
 
-  $fragments['select'][]      = 'count(*) as unread_count';
+  $fragments['select'][]      = 'COUNT(DISTINCT thread_id) as unread_count';
   $fragments['where'][]       = 'pmi.new = 1';
-  $fragments['where'][]       = 'pmi.recipient = %d';
+  $fragments['where'][]       = 'pmi.uid = %d';
   $fragments['query_args'][]  = $account->uid;
 }
 
diff -urp privatemsg/privatemsgapi/privatemsgapi.inc privatemsg_new/privatemsgapi/privatemsgapi.inc
--- privatemsg/privatemsgapi/privatemsgapi.inc	2008-09-20 21:22:20.000000000 +0100
+++ privatemsg_new/privatemsgapi/privatemsgapi.inc	2008-09-23 21:53:59.011200000 +0100
@@ -67,9 +67,6 @@ function _privatemsg_assemble_query($que
   $SELECT = array();
   $INNER_JOIN = array();
   $WHERE = array();
-  $UNION_SELECT = array();
-  $UNION_INNER_JOIN = array();
-  $UNION_WHERE = array();
   $GROUP_BY = array();
   $ORDER_BY = array();
   $QUERY_ARGS = array();
@@ -79,9 +76,6 @@ function _privatemsg_assemble_query($que
     'select'      => $SELECT,
     'inner_join'  => $INNER_JOIN,
     'where'       => $WHERE,
-    'union_select'       => $UNION_SELECT,
-    'union_inner_join'  => $UNION_INNER_JOIN,
-    'union_where'       => $UNION_WHERE,
     'group_by'    => $GROUP_BY,
     'order_by'    => $ORDER_BY,
     'query_args'  => $QUERY_ARGS,
@@ -109,9 +103,6 @@ function _privatemsg_assemble_query($que
   $SELECT = $fragments['select'];
   $INNER_JOIN = $fragments['inner_join'];
   $WHERE = $fragments['where'];
-  $UNION_SELECT = $fragments['union_select'];
-  $UNION_INNER_JOIN = $fragments['union_inner_join'];
-  $UNION_WHERE = $fragments['union_where'];
   $GROUP_BY = $fragments['group_by'];
   $ORDER_BY = $fragments['order_by'];
   $QUERY_ARGS = $fragments['query_args'];
@@ -133,18 +124,6 @@ function _privatemsg_assemble_query($que
       $str_where = '('. implode(') AND (', $WHERE) .')';
       $query .= " WHERE {$str_where}";
     }
-    if (!empty($UNION_SELECT)) {
-      $str_union_select = implode(", ", $UNION_SELECT);
-      $query .= "UNION SELECT {$str_union_select} FROM ". $primary_table;
-    }
-    if (!empty($UNION_INNER_JOIN)) {
-      $str_union_inner_join = implode(' ', $UNION_INNER_JOIN);
-      $query .= " {$str_union_inner_join}";
-    }
-    if (!empty($UNION_WHERE)) {
-      $str_union_where = '('. implode(') AND (', $UNION_WHERE) .')';
-      $query .= " WHERE {$str_union_where}";
-    }
     if (!empty($GROUP_BY)) {
       $str_group_by = ' GROUP BY '. implode(", ", $GROUP_BY) ;
       $query .= " {$str_group_by}";