Outlook on the web:
1. Go to Settings (the gear icon).
2. Select “View all Outlook settings.”
3. Go to “Mail” > “Junk email.”
4. In the “Safe senders and domains” section, click “Add”
5. Enter the email address or domain you want to add and click “Save.”

Desktop Outlook:
1. Go to the “Home” tab.
2. In the “Delete” group, click the “Junk” dropdown.
3. Select “Junk E-mail Options…”
4. Go to the “Safe Senders” tab.
5. Click “Add…”
6. Enter the email address or domain and click “OK” and then “Apply”

Your organization might also have centralized controls for safe sender lists.