How do I reduce spam emails?

By default, Microsoft Outlook and Outlook Express are installed with the preview pane enabled. You should do one of two things. Either disable the preview pane (View/Layout and uncheck show in preview pane) or disable automatic download in the preview pane
(Tools/Options/Read uncheck Automatically download messages when viewing in preview pane).

Every time you view a message in the preview pane you are opening it. This can send a verification back to the sender of the spam that the email has been opened. This validates the address to the spammer and the spam flood gates are opened.

The culprit here is HTML based email. Hidden and/or visible graphics within the email can contain a verification code that is sent back to the server when the graphic is requested to be displayed in your email client. This code ties directly to your email address in their database. Once the email is opened or viewed in the preview pane your address is validated.