Attention-flashing when a value is exceeded
 

How to write a macro so that if a value in a cell is exceeded, the excel
window will flash or turn to red?

In a financial excel spread sheet, a manager has to keep track on the total
money
every day. If the money is exceed a certain value he has to take actions.

How to make this automation by flashing or turn red or even better send
email?

Thanks
Daniel