Click the Junk Mail button. A Junk Mail window appears, as shown in Figure 47-1.
Select or clear the Enable junk mail filtering checkbox, which is initially checked by default. If you remove the checkmark, Mail won't filter out junk mail.
Click a radio button under the When junk mail arrives group. You have three choices:
Select Message ▸ Mark ▸ As Junk Mail (or click the Junk button at the top of the Mail window). The preview pane displays You marked this message as Junk Mail, as shown in Figure 47-2.
(Optional) Click the Not Junk button if a message is labeled as junk mail by mistake.
After you've identified junk mail, you can delete junk messages manually by doing the following:
If you configured Mail to route suspected junk messages to a Junk mailbox folder automatically, you should browse through this Junk mailbox folder periodically to look for any valid messages mistakenly identified as junk by Mail's filters. When you're sure the Junk mailbox folder only contains useless messages, delete your Junk mailbox folder by selecting Mailbox ▸ Erase Junk Mail.