Currently, it's very easy for any organization to generate spam e-mail since there's no requirement that they accurately identify themselves as the originator. Often, someone will receive spam which is labelled as being sent from a family or friend.
To prevent this, the data servers used to process e-mail messages should require an electronic signature which accurately identifies the originator of the e-mail. Each ISP provider should enforce this standard.
A good analogy is how we manage traffic on the highway. Every car on the highway must have a verified license plate. That license plate can be used at any time to identify the owner of the vehicle.
E-mail needs an electronic version of the license plate. The accuracy of the license plate should be enforced.