Spam filtering is built into Office 365. Spam will be delivered to your Junk Mail folder for you to examine, and the system will learn as you tell it some things are not junk.
In Outlook Online
- Right Click the junk or spam email and click mark as junk
in Outlook Desktop Client
- Right click the email in the email list and select Block Sender. This will block all email from the specific sender of the email. (IE jdoe@xyz.com)