A student is not receiving emails from their professor. The faculty member has verified that it is going to the right account, and is not getting a bounce-back error.
First, the student should check to make sure it's not being caught in the "Other" mailbox by following the steps on this guide. If that does not resolve the issue, then the faculty member's email address may be blocked in the student email. Check using the Outlook WebApp by using the instructions found here Managing Blocked/Safe Senders in the Microsoft 365 Outlook Webapp or Outlook by using the instructions found here Managing Blocked/Safe Senders in Outlook.