I use a program called MailWasher Pro from Fire Trust, a New Zealand company,
www.firetrust.com. It allows me to preview waiting messages on all 3 of my POP3 accounts and delete, bounce and/or blacklist any unwanted messages before downloading into Outlook. It's an extra step but well worth it IMO. In the slightly under 3 months I've been using it I've bounced mail from over 100 different spamming addresses; it doesn't tally duplicates but I know there have been several. I prefer to control the process rather than allowing filters to reject mail automatically.