How to exclude notifications for all junk email? (Outook 2013)

From Disable New Mail Desktop Alert for specific accounts :

There is not a direct setting for this in Outlook, but you can achieve this by disabling the generic option to display the New Mail Desktop Alert and then create a rule to display it again when mail arrives via your specified account(s).

Disabling New Mail Desktop Alert

The first step of the process is to disable the generic option to always display the New Mail Desktop Alert.

• Outlook 2003 and Outlook 2007
  Tools-> Options…-> button: E-mail Options…-> button: Advanced E-mail Options…-> option: Display a New Mail Desktop Alert
• Outlook 2010 and Outlook 2013
  File-> Options-> Mail-> section: Message arrival-> option: Display a Desktop Alert

Display alert for 1 specific account

1. Open the Rules and Alerts dialog;
   • Outlook 2003 and Outlook 2007
     Tools-> Rules and Alerts… (press OK if you get an HTTP warning)
   • Outlook 2010 and Outlook 2013
     File-> button: Manage Rules & Alerts
2. When you see the “Apply changes to this folder” drop down list at the top, make sure that the account which you want to exclude is selected here.
3. Button "New Rule…"
4. Select "Start from a blank rule" and verify that "Check messages when they arrive" or "Apply rule on message I receive" is selected.
5. Press Next to go to the Conditions screen.
6. Verify that no condition is selected and press Next.
7. A warning will pop-up stating that this rule will apply to all messages. Press "Yes" to indicate that that is correct.
8. Select the action “display a Desktop Alert”.
9. Press Next.
10. Select: 'except through the specified account' (third option from the top)
11. After completing step 10, stay in the same window from 10. Under 'Step 2: Edit the rule description (clicked an underlined value), at the bottom, click on “specified” and then select the account for which you want to see the alert.
12. Press Finish to complete the rule.

To make sure that the alert is being shown for each and every mail that is being received for your selected accounts, you must place the newly created rules all the way at the top.