Set up anti-phishing
Phishing is a malicious attack where an email looks like it was sent from a familiar source, but it attempts to collect your personal information. By default, Microsoft 365 includes some anti-phishing protection, but you can increase that protection by refining the settings. Let's take a look.
In the admin center at https://admin.microsoft.com, select Security, Policies & rules, Threat Policies, then Anti-phishing.
Select Default Policy to refine it.
In the Phishing threshold & protection section, select Edit protection settings.
Choose Enable domains to protect and select Include the domains you own and Include custom domain, then select Manage custom domain(s) to add a domain.
Choose Add trusted senders and domains. Here you can add email addresses or domains that shouldn't be classified as an impersonation.
Choose Enable Mailbox intelligence and Enable Intelligence for impersonation protection to enable enhanced impersonation results based on each user's individual sender map.
Select Enable Spoof intelligence to choose how you want to filter email from senders who are spoofing domains.
Select Save, then Close.
Your organization now has better protection from phishing threats.