Email is wonderful (so is Chat), provided it is used correctly. Look what you get in an email exchange. You get the content data plus the meta data recording who sent what, when it was sent and to whom. All of this is searchable, and all of this is usable. The biggest mistake people make with email is not sending a blind copy back to themselves. The second biggest mistake is not filing all emails for posterity. With Chat, it needs to be configured to enable all conversations to be saved.