You can configure the Auto-complete suggestions options of Outlook.com to only suggest people present in your contact list.
- To enable this option, proceed as indicated below:
- From your Outlook.com home-screen, click on Settings > More Mail settings.
Go to Customizing Outlook > Advanced privacy settings
- For the "Auto-complete suggestions" option, select "Only suggest people in my contact list"
- Click on the "Save" button to validate.