Microsoft 365 puts email, files, identity, and collaboration in one connected environment. That is convenient, but a single compromised account can affect many services. A focused checklist helps a Surrey business improve the controls that protect everyday work without turning security into a vague project.
Start with identity and admin accounts
Review administrator accounts, require strong authentication, remove stale access, and use separate admin identities where appropriate. Keep ownership documented so a departure or emergency does not leave the business locked out.
- Enable and review multi-factor authentication.
- Audit guest and inactive accounts.
- Limit administrative access to what each role needs.
Protect devices and information
Keep supported devices updated, use endpoint protection, and review how files are shared externally. Define where sensitive information belongs and who should be able to access it. Cloud convenience should not become permission sprawl.
- Review sharing links and external guests.
- Patch browsers, operating systems, and applications.
- Train staff to report suspicious messages.
Make the checklist repeatable
Security is a process, not a one-time configuration. Microsoft’s Zero Trust guidance frames access around verifying explicitly, using least privilege, and assuming breach. Digital Allo can help with cloud solutions, identity reviews, and practical security support.
- Schedule quarterly access reviews.
- Document recovery contacts and dependencies.
- Track exceptions with an owner and review date.
The checklist in order of impact
- Turn on multi-factor authentication for everyone. Microsoft’s security defaults provide a baseline for many small tenants; businesses with Microsoft 365 Business Premium or Entra ID P1 can use Conditional Access for finer control.
- Protect administrator accounts. Use separate admin accounts that are not used for daily email, keep the number of global administrators small, and keep at least one secured emergency access account.
- Block legacy sign-in methods that cannot use multi-factor authentication.
- Review mailbox forwarding rules. Attackers often add rules that silently forward or hide email.
- Limit external sharing in OneDrive and SharePoint to what the business actually needs, and set link expiry where possible.
- Enable audit logging so you can investigate later if something goes wrong.
- Check Microsoft Secure Score to see recommended actions and track progress over time.
- Plan an independent backup for mail, OneDrive and SharePoint.
Quarterly review
| Check | What to look for |
|---|---|
| Users and licences | Leavers still active, shared mailboxes with passwords, unused licences |
| Admin roles | Who holds each role and whether they still need it |
| Guests and sharing | External guests and anonymous links that are no longer needed |
| Sign-in reports | Unusual locations, repeated failures, sign-ins without MFA |
| Secure Score | New recommendations and changes since the last review |
A practical starting point
- Secure admin accounts first.
- Review sharing and inactive access.
- Turn the checklist into a recurring review.
Frequently asked questions
Is MFA enough?
MFA is an important control, but it works alongside patching, least privilege, endpoint protection, backups, and staff awareness.
Should every user have the same access?
No. Access should match the role and be reviewed as responsibilities change.
Is Microsoft 365 Business Premium necessary?
Not for every business, but it adds tools many small offices need, such as Conditional Access, device management and stronger threat protection. Compare it with the risks and the number of users who need it.
Further reading
- Microsoft Learn: Microsoft 365 admin account security
- Microsoft Learn: Security defaults in Microsoft Entra ID
- Microsoft Learn: What is Conditional Access?
- Microsoft Learn: Microsoft Secure Score
How Digital Allo can help
Digital Allo sets up and reviews Microsoft 365 for Surrey businesses, including identity, sharing and backup. Ask us for a Microsoft 365 security review and we will work through this checklist with your team.
