How can delegates get new mail notifications for another user's Inbox?

[Alan]

Hello,

Lots of our secretaries are setup as delegates and have added their
bosses' Inbox folders to their own folder list. However, they only
receive new mail notifications on their own Inbox folders and not
their bosses''.

How can they get a popup/audible notification when messages arrive in
their bosses' Inbox folders?

We tried creating a rume but they don't appear to to run automatically
on delegate folders?

Thanks,

- Alan.