2026-09-01 · Christopher Whyke, Technical Director
Microsoft 365 Security Baseline for Growing UK Businesses
The practical M365 hardening steps every UK SME should complete: MFA, Conditional Access, email authentication and backup.
Start with identity
Most Microsoft 365 breaches begin with stolen passwords. Enforce MFA for every user, disable legacy authentication, and use Conditional Access for admin roles. These changes alone remove a large share of account-takeover risk.
Email authentication and filtering
Publish SPF, DKIM and DMARC, then monitor for spoofing. Pair that with modern email security so phishing and payload delivery are blocked before users click. DMARC reporting also helps you clean up legitimate senders that fail authentication.
Backup what Microsoft does not
Microsoft retains responsibility for the service, not your data retention strategy. Back up Exchange, SharePoint, OneDrive and Entra ID objects so ransomware or accidental deletion does not become a business-ending event.
