We had a user getting hit with a load of Junk Mail and Microsoft are not detecting these as SPAM.

It seems someone has signed up this email to a load of legitimate newsletters from around the world , called an Email Bomb
They have a few options
- They are going to have to unsubscribe from each newsletter manually using the links in the emails
Try and use an Automated service ( Careful about privacy )
Bulk Clean-Up with Search and Sweep:
- If the Subscriptions tab isn’t available or doesn’t catch everything, go to your Inbox.
- Use the search bar at the top and type “unsubscribe” (no quotes). This will filter emails containing the word “unsubscribe,” which is common in promotional emails.
- Select multiple emails by holding Ctrl (or Shift for a range) and clicking them.
- Click the Sweep button in the toolbar (or right-click and select Sweep).
- Choose Delete all from [sender] and check Also block future messages to unsubscribe and remove existing emails in one step.