(The version used for this walk through is Outlook Express 6.0 using Windows XP)
1) Open Outlook Express
2) Select the 'Tools' menu (located to at the top and toward the left).
3) Highlight the 'Message Rules' option in the menu and then select 'Mail...'
4) A window called 'Message Rules' should appear.
Be sure the 'Mail Rules' tab is selected and then click the 'New...' button.
5) A window called 'New Mail Rule' will appear. In the first section, place a
check mark next to 'Where the Subject line contains specific words'.
See example below:

Words will appear in the step 3 area after selecting this option.
6) In the second section select either 'Move it to the specified folder' if
you don't want to delete the spam immediately in case something was
incorrectly labeled as spam or 'Delete it' if you simply want to delete the
spam as it arrives.

7) In the third area, click on the link that says, 'contains specific words'

This will bring up a window titled 'Type Specific Words'
8) In the top field, type '-SPAM-' so that it appears like it does in the
graphic above.
9) Click the 'Add' Button
10) Click the 'OK' button. This will close the window.
11) Now click on the 'specified' link in the third field.

(This link is only available if you selected 'Move it to the specified folder' in step #6.
If you selected 'Delete it' then please skip to step #14)
This will open a window titled 'Move'.

12) Select the folder you wish your spam to be stored in from the folders
displayed in the 'Move' window (or create a new folder by clicking on
'New Folder') and then click the 'OK' button. This should close the
'Move' window.
13) In the fourth field rename your rule. You might pick something like
'Spam Rule'.

14) Click the 'OK' button. This will close the 'New Mail Rule' window.
15) Click the 'OK' button in the 'Message Rules' window. This will close the
window.
- Your rule is now in place and should automatically sort any incoming spam mail in the manner you determined.