Invest in a filter program like Mailwasher http://www.firetrust.com/
it wont catch everything automatically from the moment it's installed but with a bit of training it'll catch the worst offenders.

Personally I would never trust Outlook to do anything for me, it was one of the first programs I uninstalled when I updated to WinXP, & never ever leave the message pane open as this can activate virii & trojans without you actually doing anything.

Windows 7 64Bit
Poser Pro 2010 SR1