To set up such a top priority filter in Mozilla Thunderbird, Netscape or Mozilla:
- Select Tools | Message Filters... from the menu.
- Click the New... button.
- Give the filter a meaningful name ("Hilmar --> Top Priority" for example).
- Select Sender from the Subject search criteria drop-down menu.
- Leave contains untouched.
- Enter the top priority person's email address.
- Under Perform these actions:, select Change the priority to.
- Make sure highest is selected.
- Finally, click OK.
If you have multiple filters, make sure the top priority filter is above any other filter that takes action when a message from your important sender arrives.

