$DB->query("SELECT ConvID FROM pm_conversations_users WHERE UserID='$UserID' AND InInbox='1' AND (ForwardedTo=0 OR ForwardedTo=UserID) AND ConvID='$ConvID'");
if($DB->record_count()==0){error(403);}
$DB->query("SELECT ConvID FROM pm_conversations_users WHERE UserID='$ReceiverID' AND (ForwardedTo = 0 OR ForwardedTo = UserID) AND InInbox='1' AND ConvID='$ConvID'");
if($DB->record_count()==0){
$DB->query("INSERT IGNORE INTO pm_conversations_users
(UserID,ConvID,InInbox,InSentbox,ReceivedDate)
VALUES('$ReceiverID','$ConvID','1','0',NOW())
ONDUPLICATEKEYUPDATEForwardedTo=0,UnRead=1");
$DB->query("UPDATE pm_conversations_users SET ForwardedTo='$ReceiverID' WHERE ConvID='$ConvID' AND UserID='$UserID'");
$Cache->delete_value('inbox_new_'.$ReceiverID);
header('Location: inbox.php');
}else{
error("$StaffIDs[$ReceiverID] already has this conversation in their inbox.");