I figured it out!

In the customer center, at the top, above the list of your Customers and Customer Jobs there is a drop-down titled New Customer & Job.

Open the drop-down and select Add Multiple Customer:Jobs.

This will open a table listing all your Customers and Jobs.

Overwrite the email you want to change.

I just did a copy/paste (CTRL+C and CTRL+V) and changed 50 files in about 30 seconds.

I hope I explained this well enough.