Preventing unwanted email (spam or Junk Email) is a pretty difficult problem. SPU has created a "defense in depth" for spam and has a dedicated filter appliance that helps reduce the problem significantly. Settings for the server based filter will effect all messages that come into your SPU email account.
For those messages that make it beyond our server email filtering devices, Outlook 2007 has its own Junk Mail Filter.
It generally is not a good idea to reply in any way to unsolicited commercial email, since replying informs the sender that your email address is actively read. Your address can then be put on a list of "verified" addresses and sold at a premium. Instead, just delete the email.
Access your Junk Mail Settings:
Please be cautious with these settings to prevent regular email from being blocked, or improperly routed to your Junk Email folder. It's a good idea to regular review the items in your Junk Email folder before they are deleted.
Mislabeled as spam:
Since SPU maintains several layers of defense against spam, the more options you actively change, the more likely individual messages could be considered spam by your configuration.
Better filtering will result in less spam, but it will increase the likelihood of individual messages being incorrectly routed to one of the holding areas for your review. The Outlook Junk Email filter will by default move email it considers Junk to the Junk Email folder.