Follow these simple steps;
You can check the filters that you currently have on your i-mail account by selecting "filter used at this moment" in the "i-mail settings" menu.
1. Select 'i-mode' by pressing the yellow 'i' button
2. Select 'i-Menu'
3. Select 'My i-mode'
4. Select 'i-mail settings'
5. Select 'i-mail filter'
6. Select the appropriate filter type and follow instructions