You can configure the spam filtering settings using your Safe Senders/Blocked Senders feature of Outlook and Outlook Web Access. 

We block emails that are listed on the Spamhaus database. The sender will receive a message back stating why the message was blocked. This only blocks known spammers.

The remaining items get moved to your Junk Email folder in Outlook/Outlook Web Access. This is where the Safe Senders/Blocked Senders feature comes in.

If you want to turn it off completely you can do that from Outlook Web Access, then Options and Click Junk E-Mail