A very effective way to reduce phishing email is to enforce only receiving email from reputable email services. If you have not heard of this type of email protection then it is time to get in contact with us.
However if the threat actors have a method of hijacking one of these reputable mail servers, then other layers of your cyber security will come into play.
This is what has happened in this zero-day attack.
Hackers exploited Salesforce zero-day in Facebook phishing attack
Clive Catton MSc (Cyber Security) – by-line and other articles