E-mail lacks authentication and this is taken advantage of by hackers because 80% of all emails are malware, phish and spam.  DMARC (Doman-based Message Authentication, Reporting and Compliance) is a new authentication standard that is emerging and supported by Google, Yahoo, AOL and Microsoft.

It’s the keystone global standard, integrating two older authentication standards and aligning them in a way that makes it possible to authenticate the identity of an email sender easily, reliably and quickly — essentially creating a white list of acceptable senders of email, and blocking unauthorized senders from delivery.

For more information you can read Deleting Email’s Original Sin: An Historical Perspective