How can an email be spoofed?

How can an email be spoofed?

Every email message sent will hold two "from" addresses.
  1. Preview from - This is the from address you see when you receive an email.
  2. Return-path - This is the from address found in the header of an email. It is used by mail servers to identify whom to notify in case a message wasn't delivered.  
A spammer would manipulate and edit one or both of the from addresses to spoof an email.