There are many approaches to blocking email spoofing. Let’s walk through a simple method using Office 365 email transport rules to prevent Example.com employees from receiving emails sent from an attacker pretending to send email from Example.com.

Login to Office 365 using an account with administrator rights.

Open the ‘Admin centers’ navigation tree on the left and click on ‘Exchange’.

Click on ‘Mail flow’.

Click on the ‘+’ sign to create a new rule.

 

Congrats, you have a shiny new anti-email spoofing rule in place!

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