Microsoft 365 Security Checklist: 10 Things Every Business Should Review
Your employees probably use Microsoft 365 every day.
They open Outlook in the morning. Share files through OneDrive and SharePoint. Meet in Teams. Work in Word and Excel. And increasingly, they may be using Copilot and other AI tools alongside all of it.
But when was the last time someone actually reviewed the security behind those tools?
Microsoft 365 includes a lot of security capabilities, but having Microsoft 365 and having it configured appropriately for your business are two different things.
So instead of asking, “Is our Microsoft 365 secure?” try these ten questions.
You may discover a few things worth reviewing.
Is MFA Protecting Every Account?
You probably already know multifactor authentication is important.
Here's the better question:
Is it actually protecting everyone?
One old account, temporary employee login, shared account, or overlooked user can create a gap even if everyone else is properly protected.
Microsoft enables MFA by default for Microsoft 365 business organizations and continues to recommend multifactor authentication as a foundational identity protection. Administrative accounts deserve even more attention because of the amount of control they can have over an environment.
What to review: Confirm which accounts are active, whether MFA applies to them, and whether there are old or unnecessary accounts that should no longer exist.
Are Your Admin Accounts Getting Extra Protection?
Not every Microsoft 365 account has the same amount of power.
An employee's account may provide access to their email and files. An administrator can potentially make changes affecting users, security settings, applications, and other parts of your Microsoft 365 environment.
That's why an admin account shouldn't simply be treated like another employee login.
Microsoft specifically warns that administrator accounts are valuable targets because of their elevated privileges and recommends additional security considerations for them.
There's also a simple principle worth remembering:
If someone doesn't need administrative access, why give it to them?
What to review: Who currently has administrative privileges, whether they still need them, and how those accounts are being protected.
Are You Still Allowing Older Ways to Sign In?
Technology doesn't always disappear when something newer replaces it.
Older applications and devices can sometimes continue using legacy authentication methods that don't support the security protections businesses rely on today.
That can create an awkward situation: you've invested in stronger account security, but an old method of connecting may still be hanging around.
Microsoft's current Conditional Access guidance includes blocking legacy authentication as one of its common recommended policies.
What to review: Ask whether legacy authentication is still being used anywhere in your Microsoft 365 environment and whether any old applications or devices depend on it.
Don't simply turn things off without checking. The point is to understand what's there before an outdated connection becomes an unexpected security gap.
Is Your Email Getting the Protection You Think It Is?
For many businesses, email is still one of the busiest doors into the organization.
And attackers know it.
Microsoft 365 includes built-in anti-spam, anti-malware, and anti-phishing capabilities, while Microsoft Defender for Office 365 can add protections such as Safe Links, Safe Attachments, and impersonation protection depending on licensing and configuration.
Microsoft recommends its Standard preset security policy as a baseline suitable for most users, with Strict protection intended for selected higher-value or priority users.
The important word here is configured.
Having a security feature available doesn't necessarily mean every employee is receiving the protection you expect.
What to review: Which email security protections your Microsoft 365 licensing includes, which policies are enabled, and who those policies actually cover.
Who Can Access Your Files?
This one is easy to overlook.
Over the years, employees create folders, Teams, SharePoint sites, shared documents, and OneDrive links. People change roles. Employees leave. Departments reorganize. Vendors and outside partners may be given access to information for a project.
Eventually, the question becomes:
Does everyone who can access something today still need access to it?
This is becoming even more important as AI enters Microsoft 365.
Microsoft's current Copilot guidance specifically tells organizations to identify overshared sites, sensitive information, risky sharing links, inactive sites, and content without appropriate ownership.
What to review: External sharing, broad sharing links, old SharePoint sites, folder permissions, site owners, and access that may no longer be necessary.
Would You Know If Someone Clicked a Dangerous Link?
Cybersecurity isn't only about keeping malicious email out.
It's also about what happens when something gets through.
Safe Links in Microsoft Defender for Office 365 can check URLs at the time someone clicks them across supported email, Teams, and Microsoft 365 applications. Microsoft describes this as an additional layer beyond regular anti-spam and anti-malware protection.
But licensing and configuration matter here too.
This is why we wouldn't recommend asking only, “Do we have email security?”
Ask:
What actually happens when an employee receives or clicks something malicious?
What to review: Safe Links, Safe Attachments, anti-phishing protections, impersonation protections, alerting, and how suspicious activity gets investigated.
When Was the Last Time Someone Reviewed Your Microsoft Secure Score?
Here's one you can actually ask your IT provider about.
What's our Microsoft Secure Score?
Microsoft Secure Score evaluates aspects of your organization's security posture and recommends actions that can improve it.
It isn't a guarantee that you're secure, and the goal shouldn't necessarily be to chase a perfect score.
Think of it more like a dashboard.
It can help reveal areas that deserve a closer look and give whoever manages your Microsoft 365 environment a way to prioritize improvements.
What to review: Your current Secure Score, which recommendations have the biggest potential impact, and which recommendations actually make sense for your organization.
Could You Recover the Information Your Business Depends On?
Most businesses don't spend much time thinking about recovery on a normal Tuesday.
That's exactly why it's worth discussing on a normal Tuesday.
What would happen if an employee accidentally deleted something important?
What if information was intentionally removed?
What if ransomware or another incident affected business data?
Microsoft 365 has retention, recovery, and resilience capabilities, but businesses should understand what protections their particular environment and licensing provide.
And there's an important distinction between:
“Our data is in Microsoft 365.”
and
“We know how we would recover the data we need.”
What to review: What information needs to be recoverable, how long it needs to be retained, what native recovery capabilities are available, whether additional backup is appropriate, and whether anyone has tested the recovery process.
Do Your Employees Know What a Microsoft 365 Attack Looks Like?
You can configure a lot of security technology.
Eventually, someone still has to decide whether to click.
And phishing doesn't always arrive as the obviously fake email people were taught to recognize years ago.
An employee might receive an unexpected Teams message.
A fake Microsoft sign-in page.
An MFA request they didn't initiate.
A phone call from someone claiming to be IT support.
That's why employee awareness still matters.
The goal isn't to turn every employee into a cybersecurity expert.
It's to give them a simple instinct:
If I wasn't expecting this, I should verify it before I act.
What to review: How employees report suspicious activity, whether cybersecurity awareness is discussed regularly, and whether people know what to do when something doesn't feel right.
Before You Add More AI, Have You Reviewed Who Can Access What?
This might be the newest item on your Microsoft 365 security checklist.
Copilot can make it much easier for employees to find, summarize, and work with information they already have permission to access.
That's useful.
It also makes old permissions worth another look.
Imagine an employee was accidentally given access to a SharePoint location several years ago. Maybe they never knew it existed.
Now introduce an AI assistant designed to help them find information across the content they're permitted to use.
Suddenly, that old permissions decision becomes a lot more important.
Microsoft's current 2026 guidance for Copilot specifically recommends identifying and addressing oversharing and sensitive content, then establishing controls designed to prevent new oversharing.
What to review: SharePoint and OneDrive permissions, external sharing, sensitive information, site ownership, AI policies, and what company information employees and AI tools can access.
How Many Boxes Could You Check?
If you couldn't confidently answer all ten questions, that doesn't necessarily mean something is wrong.
It means you've found something worth asking about.
Microsoft 365 continues to change. So do cyber threats. Employees come and go. New applications get added. Files get shared. Permissions change. And now AI is introducing another way for employees to interact with company information.
Security shouldn't be something you configure once and assume is still working exactly the way you intended three years later.
It needs an occasional review.
Start With These 10 Microsoft 365 Security Questions
☐ Is MFA protecting every account?
☐ Are administrative accounts getting additional protection?
☐ Is legacy authentication still allowed?
☐ Are the right email security protections enabled?
☐ Who can access your SharePoint and OneDrive files?
☐ Are malicious links and attachments being checked?
☐ When was Microsoft Secure Score last reviewed?
☐ Could you recover important Microsoft 365 data?
☐ Do employees know how to respond to suspicious activity?
☐ Are your permissions ready for AI and Copilot?
But someone should.
At TriTech, we help businesses across Southeastern Wisconsin manage Microsoft 365 as part of the bigger technology picture, from user accounts and cybersecurity to ongoing IT support and planning.
If some of these questions made you wonder what's happening inside your own Microsoft 365 environment, that's a good place to start the conversation.
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