If your email is set up on BIS, you can login in to BIS on your computer and set up filters so the spam messages are not pushed to your BlackBerry. I have a couple of email accounts that get a ton of spam and I have most of it filtered so not much gets pushed to my device. If you are using your ISP email, gmail or yahoo, etc, you should also be able to turn on spam filtering for those accounts to stop it at the server level.