To retrieve deleted messages:
■ If Mail is set up to move deleted messages to a Trash mailbox, select that mailbox and drag the message you want to save into another mailbox.
■ If Mail is set up to mark deleted messages, choose View > Show Deleted Messages, then select a message and choose Message > Undelete.
The Show Deleted Messages command is available only if you havent selected an accounts option in the Mailbox Behaviors pane in Mail preferences to move deleted messages to the Trash mailbox or to a separate folder. When the option is deselected, deleted messages stay in the mailbox where you deleted them. You can then choose to show or hide them.