newmail_popup not working

[Network]

The newmail_popup has never worked with our imp-2.2.4.  How can I contact
the author to have this debugged -or- advise given?

newmail_popup ...
horde/imp/config/defaults.php3:$default->newmail_popup  = true;
-
refresh_delay ..
horde/imp/config/defaults.php3:$default->refresh_delay                  =
'300';

If there is something else that needs to be set please direct me to the
proper doc.  I've done all that I know how to do.