A new default policy is being deployed for Office 365 ATP (Advanced Threat Protection) to protect you against phishing.
The new policy is/will be available through the Security and Compliance administration portal (https://protection.office.com/)
From there, reach out the Threat Management\Policy section and then click on ATP anti-phishing option
Then the Default policy is not displayed in the list of policy; it is displayed using the button Default policy
By clicking on this button, this will display the configuration blade for the policy and you will be able to edit, but you can not change the name, disable or delete it.
You can define which user(s) to apply the policy, which domains (either your domains {all the domains you own and have associated with O365] or a custom domain {like a partner domain}), actions or anti-phishing level (from standard to aggressive – I would say be careful with the aggressive level)
