Outlook 2007 sending mail to Junk and Spam

[vavs]

I am running Windows 2003 on my server and Office 2007 on all my PCs. I am seeing personally and have had input from several users that some of their mail is going to the spam and junk folders. I have a system generated email that is going to spam even though I have a rule that sends it to a specific folder. Has anyone experienced the same behavior. One of my users has had internal email address mail sent to his spam.