There are two ways to pull an archived Message back into your field of view.
Method 1:
Reply to the archived Message. This brings it back to the active Messages in your Inbox.
Select Inbox in the Left-Hand Menu.
Navigate to the Archived tab.
Select the Message you want to reopen.
Type a Message in the Reply box.
Select Send.
The Message will move back to Inbox once the recipient has replied to your Message.
Note: Messages cannot be reopened if the contact or the employee has been archived.
Method 2:
If you do not want to send an new message to a Contact, you can pin the archived message. The message will be moved to your Pinned tab. This is an easy way to identify a message that will need your attention in the future.