A spam filter SHALL be enabled

Contributed by Michael Soule with Thomas SchmidtAll contributors →

Part of CISA · Exchange Online · Anti-spam · All checks

Run this check

Invoke-Maester -TestId CISA.MS.EXO.14.1

Overview

A spam filter SHALL be enabled.

Rationale: Spam is a constant threat as junk mail can reduce user productivity, fill up mailboxes unnecessarily, and in some cases include malicious links or attachments. Filtering out spam reduces user workload burden, prevents junk mail congestion, and reduces potentially malicious content exposure.

Remediation action

1. Sign in to Microsoft 365 Defender.
2. In the left-hand menu, go to Email & Collaboration > Policies & Rules.
3. Select Threat Policies.
4. From the Templated policies section, select Preset Security Policies.
5. Under Standard protection, slide the toggle switch to the right so the text next to the toggle reads Standard protection is on.
6. Under Strict protection, slide the toggle switch to the right so the text next to the toggle reads Strict protection is on.

Note: If the toggle slider in step 5 is grayed out, click on Manage protection settings instead and configure the policy settings according to Use the Microsoft 365 Defender portal to assign Standard and Strict preset security policies to users | Microsoft Learn.

Related links

• Defender admin center - Preset security policies
• CISA 14 Inbound Anti-Spam Protections - MS.EXO.14.1
• CISA ScubaGear Rego Reference

Details

Every attribute of this check

Field	Value
Test ID	CISA.MS.EXO.14.1
Severity	High
Suite	CISA
Product	Exchange Online
Related products	Defender
Feature	Anti-spam
Area	Email and collaboration protection
Resource type	Tenant
User impact	Low
Implementation cost	Low
MITRE ATT&CK	T1566 Phishing
Supports benchmark	CISA SCuBA Secure Configuration Baselines for Microsoft 365 (version ScubaGear main, 2026-10-11), requirement MS.EXO.14.1
Criticality	SHALL
Upstream requirement	Moved to MS.SECURITYSUITE.6.1v1 (was MS.EXO.14.1v2)
Supports controls	cisa-scuba:MS.EXO.14.1, nist-800-53-r5:SI-8
PowerShell test	Test-MtCisaSpamFilter
Services	ExchangeOnline

Source

• Test: tests/cisa/exchange/Test.CISA.MS.EXO.14.1.ps1
• Documentation: tests/cisa/exchange/Test.CISA.MS.EXO.14.1.md