To avoid losing emails from a school or other contacts I suggest changing your Junk Email Options:
From the Home window, click the Junk ribbon at the top and select Junk E-mail Options.
Make sure the option No Automatic Filtering is selected, we recommend this setting to avoid losing emails.
Click on the Safe Senders tab, here you can specify the email or domain addresses which are safe to receive emails from. You can Add, Edit, Remove, Import, and Export addresses. If you were to whitelist a school domain, you would only add the @domain.com for example. This ensures that any emails coming from any of the school staff should be delivered without issues.
