Microsoft 365 is where many organizations manage email, files, calendars, collaboration, identity, and daily communication. Because so much business activity depends on it, small security gaps can create large problems if they are not reviewed regularly. A Microsoft 365 security review is not just for large companies or organizations with dedicated security teams. It is a practical way for business owners, managers, operations staff, and technology decision makers to understand how their environment is configured, where risk may exist, and what should be improved before an account compromise, data exposure, or access issue occurs. The goal is not to make everything complicated. The goal is to know what you have, how it is protected, and whether the current settings match how your organization actually works. Start With User Accounts and Access User accounts are one of the most important places to begin. If an account has too much access, belongs to a former employee, or does not require strong authentication, it can become a serious risk. A basic review should include: Active users Former employees or inactive accounts Administrator accounts Shared accounts Guest users Group memberships License assignments For example, an organization may discover that a former employee still has an active Microsoft 365 account because the account was never fully removed after offboarding. Another common issue is finding users with administrator roles that they no longer need. Access should match the person’s current job duties. When roles change, access should be reviewed and updated. Confirm Multi-Factor Authentication Is Being Used Correctly Multi-factor authentication, also called MFA, is one of the most important protections in Microsoft 365. It helps protect accounts even if a password is stolen or guessed. During a Microsoft 365 security review, check whether MFA is required for all users, especially administrators. Also review whether there are exceptions. Exceptions may be necessary in some cases, but they should be documented and approved. Important questions include: Is MFA required for all users? Are administrator accounts protected with MFA? Are there any users excluded from MFA? Are MFA methods current and secure? Are users trained on MFA prompts and suspicious sign-in attempts? MFA should not be treated as a one-time setup item. It should be reviewed regularly to make sure it is still working as intended. Review Administrator Roles Carefully Administrator permissions should be limited to the people who truly need them. Too many administrators can increase risk and make it harder to control changes. A practical review should look at who has access to roles such as Global Administrator, Exchange Administrator, SharePoint Administrator, Teams Administrator, and User Administrator. The question is simple: does this person still need this level of access? For example, a staff member may have been given elevated access during a project but never had that access removed. Over time, these extra permissions can build up and create unnecessary risk. Administrator accounts should also use strong authentication, separate accounts when appropriate, and careful documentation. Check Email Security Settings Email remains one of the most common ways attackers try to reach organizations. Microsoft 365 includes security settings that can help reduce phishing, spoofing, malware, and suspicious attachments. A review should include: Anti-phishing policies Spam filtering Malware protection Safe links and safe attachments if available Quarantine settings External sender warnings Domain authentication records such as SPF, DKIM, and DMARC Even basic improvements can help. For example, adding an external sender warning can help staff pause before trusting a message that appears to come from a vendor, partner, or executive. Email security should be reviewed from both a technical and operational perspective. The settings matter, but so does how staff report suspicious emails and how those reports are handled. Review File Sharing and Collaboration Settings Microsoft 365 makes it easy to share files through SharePoint, OneDrive, and Teams. That convenience is useful, but it also needs to be managed. A security review should check how files can be shared inside and outside the organization. It should also review whether anonymous links are allowed, whether guest access is enabled, and whether sensitive files are being shared too broadly. Helpful questions include: Can users create anonymous sharing links? Are external guests allowed? Are shared links set to expire? Are sensitive folders restricted? Are Teams and SharePoint permissions documented? Are old external sharing links reviewed? For example, a department may create a folder for a short-term project and share it externally. Months later, that link may still be active even though the project is finished. Regular reviews help catch those situations before they become problems. Look at Device and Endpoint Controls Microsoft 365 security is not only about cloud settings. The devices that access Microsoft 365 also matter. Organizations should review whether devices are managed, whether users are accessing company data from personal devices, and whether basic security controls are in place. This may include: Device enrollment Compliance policies Password or PIN requirements Encryption Operating system updates Lost device procedures Access from unmanaged devices For organizations using Microsoft Intune, device compliance policies can help decide whether a device should be allowed to access company data. For smaller organizations, even a basic device inventory is a useful starting point. Review Sign-In Activity and Risk Indicators Sign-in logs can provide useful warning signs. They may show failed login attempts, unusual locations, repeated password attempts, or access from unfamiliar devices. A review does not need to be overly complex. Start by looking for patterns that do not make sense. Examples include: Sign-ins from unexpected countries Repeated failed login attempts Successful sign-ins at unusual times Legacy authentication attempts Users with frequent account lockouts These details can help identify accounts that may need password resets, MFA review, or closer monitoring. Make Sure Offboarding Is Documented Offboarding is one of the most common places where security gaps happen. When an employee, contractor, or volunteer leaves, access should be removed in a timely and consistent way. A strong offboarding process should include: Disabling the user account Removing licenses when appropriate Blocking sign-in Resetting passwords if needed Removing group memberships Transferring mailbox or OneDrive data Removing access to shared systems Documenting completion The process should be written down so it does not depend on memory. A simple checklist can prevent missed steps. Review Security Documentation Security settings are easier to manage when they are documented. Without documentation, it becomes difficult to know what was configured, why it was configured, and who approved it. Useful documentation may include: Microsoft 365 administrator list MFA policy notes Conditional access policy notes Offboarding checklist User onboarding checklist Device inventory Shared mailbox list External sharing process Security incident notes Documentation does not need to be complicated. It needs to be clear, current, and easy for the right people to find. Create a Practical Review Schedule A Microsoft 365 security review should not happen only after something goes wrong. It should be part of normal operations. A practical schedule may include: Monthly review of inactive accounts Monthly review of administrator roles Quarterly review of external sharing Quarterly review of MFA exceptions Quarterly review of devices and compliance Annual review of policies and documentation The schedule should match the size and risk level of the organization. Smaller organizations may start with a quarterly review and build from there. What a Good Microsoft 365 Security Review Should Produce The review should result in clear findings, not confusion. At the end, decision makers should understand what was checked, what needs attention, and what should happen next. A useful review may produce: A list of security gaps Recommended fixes Priority levels Documentation updates Accounts or permissions that need cleanup Settings that should be changed Follow-up tasks for staff or IT support The value of the review is not only in finding problems. It is in helping the organization make informed, practical improvements. Conclusion Microsoft 365 is a powerful platform, but it needs regular review. Accounts, administrator roles, MFA, sharing settings, email protection, devices, and documentation all play a part in keeping an organization secure. A Microsoft 365 security review helps organizations catch issues early, reduce avoidable risk, and improve daily operations before a problem happens. Need help applying this? J3 Systems Group LLC helps small businesses and nonprofits turn practical IT guidance into clear next steps. Request a Consultation Back to Resource Center
