This free spam blocker will let check your email before you launch Outlook Express to download it. You can see the subject, from address, and file size, then check a box to delete it from the server. You can add email addresses to a blacklist for automatic deletion. After processing your mail in Mailwasher, you can have your email program launch automatically.
I find that it saves me from visiting my mail server to delete unwanted emails. A few still get through, but it reduces the amount of trash that I download to my PC.