Microsoft 365
Microsoft 365 Security Basics
For many small businesses, Microsoft 365 houses critical client details and email systems. Review these security baselines to secure your tenant.
Reviewed July 10, 2026
Key Microsoft 365 Security Baselines
Administering Microsoft 365 requires active coordination to prevent account takeovers. Review these standard configuration domains:
- Enforce Multi-Factor Authentication (MFA): MFA adds an important barrier when a password is stolen. Depending on licensing and organizational needs, review Microsoft Entra security defaults or appropriate Conditional Access policies.
- Establish Role-Based Access: Only assign Global Administrator privileges to accounts that strictly require them. Use standard user roles for daily email and file sharing to limit exposure if an account is compromised.
- Disable Legacy Authentication: Basic authentication is the problem, not the IMAP and POP protocols themselves. Exchange Online has disabled Basic authentication, while supported clients and applications can use IMAP or POP with OAuth. Identify and replace clients that cannot use modern authentication.
- Monitor Mail Forwarding Rules: A common post-compromise tactic is creating silent mail rules that forward business emails to external addresses. Regularly audit forwarding rules in the Exchange admin center.
- Set Password Best Practices: Avoid scheduled password expirations, which often lead users to choose weaker, sequential passwords. Focus instead on unique, complex passwords stored in a manager.
Need Help Hardening Your M365 Setup?
Decker Tech Services provides remote support to help small businesses configure security baselines, review active user privileges, and set up MFA. Speak directly to a local, security-focused professional about securing your business email.