Hi Terri R!
I'm sorry as I understand how frustrating it can be to receive a large amount of spam emails. While it's not possible to completely eliminate spam
Have you tried to unscribe from the email? Check the content of the mail, you will see unscribed button, follow the link to unsubscribe from the mail. This should eventually eliminate the large junks of mail from the domain
Also, you can try to Block senders or domains:
To do this:
Right-click on an email from onmicrosoft.com in your inbox.
Select "Junk" from the context menu, and then click on "Block Sender" or "Block Sender's Domain."
Outlook will move the email to your junk folder and automatically block future emails from that sender or domain.
Kindly let me know, if you require additional assistance, I will be glad to help further.
Best Regards,
Shakiru