Managing Zimbra Spam Mail Options (Junk folder)
1.Go to the Preferences in the left menu click on Mail to display the Mail Options page.
2.Scroll to the Spam Mail Options section.
3.In the Block messages from text box, enter email addresses that should always be treated as junk. You can list up to 100 addresses.
4.In the Allow messages from text box, enter email addresses you trust that for some reason end up in your Junk folder, such as newsletters you subscribe to. Messages from these email addresses are never blocked. You can list up to 100 addresses.