If you do not want to keep read messages in your Inbox or Sent tab, you can archive them. If you archive a message, you can still move it back to your Inbox or Sent tab by clicking on the Restore link on the Archive tab.
If you do not want to keep read letters in your Inbox, you can archive them. If you archive a letter, you can still move it back to your Inbox by clicking on the Restore link on the Archive tab.