The Junk Mail options in Mac Mail are designed to keep junk e-mail messages, also known as spam, from cluttering your Inbox.You can change any of these Junk E-mail Filter options for the kind of protection that you want.

Warning: it is recommended that you periodically review the messages in your Junk E-mail folder to ensure that you are not missing any legitimate messages.

Setting your Junk Mail preferences:

1. In Mac Mail, click on the Mail menu, then click Preferences.
2. When the dialog box pops up, click on the Junk Mail icon.
3. Change your Junk Mail options as desired. 

 

Mark a Message as not Junk:

If a message has been incorrectly flagged as Junk, you can restore the email to your inbox. To correct one or more messages that have been wrongly classified as junk, select the messages and click thumbs up in the toolbar or the Not Junk button at the top of the email message.

Alternately, choose the Message Menu, hover over Mark, then select As Not Junk Mail.