Office Protect Settings - Block Top Spamming Countries

The Office Protect team pre-determined a list that includes countries with the highest ratio of spam emails versus real emails. You can tweak the list to fit your organization's reality. We will adjust the Exchange Anti-Spam policy accordingly.

All emails from the countries listed will be blocked if the setting is enabled. The recipient will not receive any notification that an email was blocked.

You can find the setting in the Security Center, in the Threat Management/Policy/Anti-Spam section.

Operation to look for in the Unified Audit Logs: Set-HostedContentFilterPolicy     

Microsoft’s documentation about Anti-Spam policy: https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/configure-your-spam-filter-policies?view=o365-worldwide