Do I use IMAP?
This guide will help you find out if you are using IMAP.
Outlook Express
1. Open Outlook Express and click on "Tools"
2. Click on "Accounts..."
3. Choose "Mail"
4. Choose your mail account and click "Properties"
5. Choose "Servers"
6. What does it says in: "My incoming mail server is a server"?
If it says IMAP you're using it, otherwise not.