Hide empty fields during sendmail - or before?

Hide empty fields during sendmail - or before?

I was curious if I can hide fields in any way that have a null value so that they are not sent via email. Here is an example:

What it currently is:
Location: New Mexico
Product 1: 6000
Product 2: null
Product 3: null
Product 4: 1500
Product 5: null

What I want it to look like:
Location: New Mexico
Product 1: 6000
Product 4: 1500


Any ideas?