Trash automatically emptying

Why are the messages in my Trash bin disappearing? Does Hotmail automatically empty my Trash bin? I don't want that to be happening because sometimes I need to go back in my Trash to retrieve something. Sometimes I delete something by mistake and don't realize it till weeks later. Then it's too late to retrieve it back from Trash because I think Hotmail empties it out automatically! How can I change that? Is there a setting to prevent automatic emptying??