Leopard 10.5 & Snow Leopard 10.6:
- Click Apple menu, choose System Preferences.
- From the View menu, choose Time Machine, Click “Select Backup Disk”.
- Choose a disk where backups will be stored, then click “Use for Backup”.
Tiger 10.4:
To back up entire mailboxes (where Mail stores messages), such as your Inbox, follow these steps:
- Quit Mail if it’s open.
- From the Finder’s Go menu, choose Home.
- Open the Library folder.
- Copy the folder “Mail” to your backup location, such as a different volume or burnable disc. Important: Do not remove the Mail folder from ~/Library. If you’re backing up to the same volume, hold the Option key as you drag the folder to make a copy instead of moving it (a “+” cursor appears).
You can restore backed-up mailboxes at any time by quitting Mail and following the above steps, except for the last step where you copy your backed up Mail folder to ~/Library, instead of from it.