A new Microsoft 365 tenant may seem ready once Outlook and Teams work. Yet the initial setup determines how employees sign in, how administrators recover access and how the business handles lost devices or departing staff. These seven checks give an owner and IT administrator a practical starting conversation, not a substitute for a documented risk assessment.
1. Inventory ownership and administrators
Confirm the tenant is owned by the business, which domain names are connected and who can contact Microsoft or the licensed reseller. Keep a current list of administrators and recovery procedures. Routine daily work should not depend on one person's global administrator account. Use least-privilege roles where the tasks allow them.
2. Require appropriate MFA
Microsoft documents security defaults for organizations using Entra ID Free and Conditional Access for suitably licensed tenants. Review which option applies before changing policies. Prefer strong authentication methods, protect privileged accounts and create a tested emergency access process. Turning on prompts without staff preparation can interrupt the business and create unsafe workarounds.
3. Review email security and domain records
Verify accepted domains and the mail-routing, SPF, DKIM and DMARC configuration appropriate to the organization. Check mailbox forwarding rules and external access. Anti-spam controls reduce risk but cannot make every attachment safe. Train employees to verify unusual payment and credential requests by a separate trusted channel.
4. Match licenses and access to job roles
Assign appropriate licenses and permissions for actual responsibilities. Review guest accounts, shared mailboxes, groups and file-sharing policies. A former contractor may retain access even after their mailbox license is removed. Keep account provisioning and offboarding checklists so access changes are both prompt and documented.
5. Configure devices and collaboration
Decide which devices are managed, how lost computers are handled and where work files should be stored. Review SharePoint and OneDrive sharing policies with the people who use them. Avoid forcing every employee into one broad sharing rule. Test day-to-day collaboration with approved external partners rather than assuming a setting is secure because it is restrictive.
6 and 7. Plan recovery and review
Know retention, deleted-item recovery and independent backup requirements for the organization's data. Cloud service availability is not the same as a full business continuity plan. Test how administrators regain access and how a representative file is recovered. Review sign-in activity, permissions and vendor recommendations periodically; document who owns each action.
Assign ownership for ongoing security checks
Determine who reviews sign-in alerts, approves new employee access, manages the domain registrar and controls emergency administrator recovery. These responsibilities should not exist only in one technician's inbox. Protect recovery procedures and review who can access them, particularly after a staffing change.
Plan a short follow-up after employees begin using Exchange, Teams, OneDrive and SharePoint. Check whether sharing settings meet real collaboration needs and whether unexpected exceptions are accumulating. Make policy changes using supported Microsoft guidance, document the reason and test the effect before enforcing them across every account.
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Further reading from trusted sources
Illustrative photography by Joyce Toh on Pexels . Images do not depict Arbor Computers clients or employees.
