KOrn is a KDE-compliant X11 program that monitors UNIX mailbox files for incoming and unread messsages. It periodically scans each mailbox and displays the number of unread messages it contains in a small on-screen button. Features include:
Per-box scan frequency (poll time)
Horizontal or vertical layout of buttons
Per-box customization of commands to be executed on new mail notification and button click
Fairly simple dialog for setup and customization
Doesn't use Xt/Xaw :-)