Why default settings aren’t enough
Microsoft 365 includes strong security capabilities, but many of them are not fully enabled out of the box, and default configurations are designed to work broadly across many types of organizations rather than to match any one business’s specific risk profile. Reviewing and adjusting these settings is a practical step every growing business should take, rather than assuming the platform is fully locked down by default.
Start with identity: multi-factor authentication and admin accounts
Identity is the foundation of Microsoft 365 security. Multi-factor authentication (MFA)—which requires a second verification step beyond a password, such as an authenticator app prompt—significantly reduces the risk of an account being accessed by someone who has only obtained a stolen password.
At minimum, MFA should be enabled for every user, and administrator accounts deserve particular attention: they should be limited to the smallest number of people who genuinely need elevated access, and used only for administrative tasks rather than daily email and document work.
Reduce risk with Conditional Access
Conditional Access is a Microsoft Entra ID capability that lets an organization apply rules about how and when access is granted—for example, requiring MFA when someone signs in from an unfamiliar location or device, or blocking access entirely from unexpected regions. For growing businesses without a dedicated security team, starting with a small number of clear, well-tested Conditional Access policies is more practical than attempting a fully comprehensive policy set on day one.
Protect email from phishing and malicious links
Email remains one of the most common ways attackers attempt to gain access to a business. Microsoft 365 includes anti-phishing and safe-link protections that can be tuned beyond their default configuration, and it is worth confirming that:
- Suspicious or spoofed sender domains are flagged or blocked.
- Links and attachments in email are scanned before a user can open them.
- Staff have a simple, known way to report suspicious emails.
No email filter catches everything, so pairing these protections with basic staff awareness remains important.
Control sharing and permissions in SharePoint, OneDrive and Teams
Microsoft 365’s collaboration tools make it easy to share files and folders—sometimes more easily than an organization intends. It is worth periodically reviewing:
- Whether external sharing is allowed by default, and if so, under what conditions.
- Whether links are set to expire or require sign-in, rather than remaining open indefinitely.
- Whether sensitive folders or sites have broader access than they should.
These settings are usually adjustable at the organization level, rather than needing to be corrected file by file.
Manage the devices that connect to Microsoft 365
Microsoft 365 security is only as strong as the devices accessing it. Devices that are unmanaged—not enrolled in any endpoint management policy—make it harder to enforce consistent security standards like encryption, screen locks, or minimum operating system versions. Growing businesses should have a clear picture of which devices, managed or not, are connecting to company data.
A practical Microsoft 365 security checklist
- Multi-factor authentication is enabled for every user, without exception.
- Administrator accounts are limited to those who need them and used only for admin tasks.
- At least basic Conditional Access policies are in place and tested.
- Anti-phishing and safe-link protections are reviewed, not left entirely at default.
- External sharing settings for SharePoint, OneDrive, and Teams have been reviewed deliberately.
- There is a clear inventory of devices accessing company data, managed or not.