Archiving a Message
You can archive any messages in your account if you wish to do so. Archiving a message from your Inbox or Sent folders will not affect the status of that message in your co-parent’s account. Additionally, all moved and archived messages will remain chronicled in the All Messages folder.
Tip: If you would like to archive all of the messages within a folder click the checkbox located at the very top of the list of messages and then click the "Archive" button.