I am working on a purchase order form, in which I have several fields with customer info, provider info, etc. Among this fields a have a Total field, the final cost of the order. If this value is less or equal to 1000 it doesn't need to be approved so I need to send it to email addressA. But if the Total value is more than 1000 it needs to be aproved, so I need to send emails to email addressA, email addressB and email addressC. 

How can I do this?