How to block unwanted email accounts from Office 365

By Niki Eyyani

You may be wondering why anyone would need to block an email account in Office 365. The answer is simple, it’s to keep your organization protected from malicious email accounts. As we all know phishing attacks are one of the biggest security challenges both individuals and companies face in keeping their information secure. Hackers attack via email to gain access to passwords, credit card information, or other sensitive data. So, not only should we be more vigilant, when we receive fraud emails, by confirming the authenticity of the emails before sharing any information, but you can also protect your organization by blocking malicious email accounts from your Office 365 and prevent these phishing emails from even reaching your organization’s inboxes.

Here’s how:

  1. After logging in to Office 365, go to “Admin”
  2. Under Admin Centers, click “Exchange”

  1. Under Exchange, Click “Protection”
  1. Under Protection, you will find a horizontal tab, Click “Spam Filter”
  1. Click on the “Edit” icon
  1. Select “Block Lists” and add the email account that you want to block by clicking on the “+” icon
  1. If you are blocking multiple emails, separate each email with a semi-colon “;” then click “OK”. This will block the listed email account(s) on Office 365.

To learn how to block malicious domain in Office 365, as well as malicious email accounts and domain in Exchange 2013/2016 and Outlook 2016, visit