imp-2.2.4 and newmail_popup

[Network]

$default->newmail_popup                  = true;
$default->refresh_delay                  = '300'

Is there something else that needs adjustment?  Nothing is popping up
notifying us of new mail.
-
Software ....
OS/FreeBSD-4.2-Stable
PHP Version 4.0.4pl1
IMAP-uw c-Client Version 4.1
Mysql= Client API version 3.23.32
Apache Version Apache/1.3.17
mod_ssl/2.8.0 OpenSSL/0.9.6