You never know, an unsolicited but legitimate email might just come in useful.
Block an email address When you block a sender, their messages will go to your Spam folder.
Note: You will need to first to get support.
This article is for Outlook Web App, which is used by organizations that manage email servers running Exchange Server 2013 or 2010.
The result: About 35-50 emails a day that qualify as spam down to 5 or so a day.
If you have subscribed some websites then you can also unsubscribe by going to individual name.