Urgent, no action required
Urgent, action required
Important but not urgent
Important requires action
Not important
For information/To read
To read and action
I agree that it would be a pain to have so many categories. What is the difference between urgent (no action needed) and important but not urgent? I would consolidate those. I agree with Atlanta's categories and would use something similar.
If you use the flags, she can sort on them and she can right mouse click on the email and select completed.