Microsoft 365 Security: Features You Should Enable Today

Unlocking Microsoft 365's Security Potential

If your business uses Microsoft 365, you're sitting on a goldmine of security features—most of which are probably turned off or misconfigured.

This guide covers the essential security settings every M365 administrator should enable.

Essential Security Features

1. Multi-Factor Authentication (MFA)

Priority: Critical

MFA should be enabled for every user, with no exceptions. Microsoft reports that MFA blocks 99.9% of automated attacks.

How to enable:

Go to Azure Active Directory

Select Security > MFA

Configure per-user MFA or Conditional Access policies

Use Security Defaults for basic protection

2. Conditional Access Policies

Priority: High

Conditional Access lets you define when and how users can access your systems:

Block access from high-risk locations

Require MFA for sensitive applications

Limit access to compliant devices only

Restrict access based on user risk level

3. Email Security Settings

Anti-Phishing Policies

Enable mailbox intelligence

Configure impersonation protection

Set up spoof intelligence

Safe Links and Safe Attachments

Enable URL scanning at time of click

Configure attachment sandboxing

Block known malicious file types

4. Data Loss Prevention (DLP)

Prevent sensitive data from leaving your organization:

Create policies for sensitive information types

Configure email rules for credit cards, SSNs, etc.

Set up alerts for potential data leaks

Enable sensitivity labels for document classification

5. Audit Logging

You can't protect what you can't see. Enable comprehensive logging:

Unified Audit Log

Mailbox auditing

Admin activity logging

Sign-in logs

6. Mobile Device Management

If users access M365 from mobile devices:

Require device enrollment

Configure app protection policies

Enable remote wipe capabilities

Set password requirements

Quick Wins: Enable These Today

Security Defaults

If you're just getting started, enable Security Defaults in Azure AD. This provides baseline protection including:

Required MFA for all users

Blocked legacy authentication

Protected privileged actions

Block Legacy Authentication

Legacy authentication protocols don't support MFA and are a common attack vector. Block them in Conditional Access.

Configure Alert Policies

Set up alerts for:

Unusual email forwarding rules

Suspicious sign-in activity

Malware detection

Failed login attempts

Advanced Security Features

Microsoft Defender for Office 365

If your license includes Defender for Office 365, enable:

Safe Attachments for SharePoint, OneDrive, and Teams

Safe Links for Teams

Anti-phishing protection with mailbox intelligence

Real-time reports and threat investigation

Azure AD Identity Protection

Automatically detect and remediate identity risks:

Risk-based Conditional Access

Automated investigation and response

Compromised credential detection

Implementation Best Practices

Phase Your Rollout

Don't enable everything at once. Start with:

**Week 1**: Security Defaults or basic MFA

**Week 2**: Email security features

**Week 3**: Conditional Access policies

**Week 4**: DLP and advanced features

Communicate with Users

Security changes affect workflows. Communicate clearly:

What's changing and why

How it affects their daily work

Where to get help

Monitor and Adjust

After implementation:

Review audit logs regularly

Adjust policies based on feedback

Stay current with new features

Conclusion

Microsoft 365 includes powerful security features—but only if you enable them. Start with the basics and progressively enable more advanced features as your security maturity grows.

*Need help securing your Microsoft 365 environment? MTH IT Solutions provides M365 security assessments and implementation services.*