PS: generally speaking, it’s only a word anyway, and there are css classes associated that would let you use the same background color as a “new” order (for example)

furthermore, you could also simply change “Acknowledged” to “New” (or whatever else you want it to be – maybe “New- Viewed” or something so at least there’s some distinction between the 2) in wppizza->localization “Admin Order History – Order Statuses”

then YOU have set up something that sends those emails.
the plugin does not do that natively