iCloud: Archive email messages
You can quickly move selected email messages from your Inbox to the Archive folder so you can read them at a later date. Unlike email messages you move to the Trash, archived email messages remain in your Archive folder until you delete them.
Select one or more messages in the message list, then click the Archive button in the toolbar.
If you don’t see the Archive button in the toolbar, click the Action pop-up menu in the sidebar, then choose Preferences. In the General pane, select “Show Archive icon in the toolbar.”
To select several adjacent messages, click the first one, then Shift-click the last one. To select multiple nonadjacent messages, Command-click them on a Mac or Control-click them on a Windows computer.
You can read archived email messages, and then move them into other folders or mark them as junk mail.