How secure is your Microsoft 365 environment? 5 common mistakes

Microsoft 365 has become the standard for many Belgian businesses. Email, calendar, Teams, file sharing — it works well and it's affordable. But what many small businesses don't realise: the default settings of Microsoft 365 aren't enough to protect your business.

The security of your Microsoft 365 environment is a bit like the lock on your front door. It's there, but if you never actually lock it, it's not doing much good.

In practice, I regularly visit small businesses in Hasselt and the surrounding area where Microsoft 365 security has never really been reviewed. Not out of negligence, but simply because nobody thought of it. Below are the five mistakes I encounter most often — and how to fix them easily.

Mistake 1: Multi-factor authentication (MFA) not enabled

This is by far the biggest and most common mistake. At more than half of the small businesses I visit for the first time, MFA isn't turned on — or only for one person.

MFA means you need a second form of verification in addition to your password to log in. Usually through an app on your phone. It might sound annoying, but it blocks more than 99% of account takeovers.

Without MFA, all a hacker needs is to guess or steal your password (through a phishing email, a data breach, or simply because the password was too simple). With MFA, that's not enough.

What to do: enable MFA for all users. Not just the business owner, but also the bookkeeper, the office manager, and the intern. One weak link is all it takes.

Mistake 2: Everyone is an administrator

In a small business, it's tempting to give everyone admin rights. "That way everyone can always access everything." But that's exactly the problem.

If an account with admin rights gets hacked, the attacker has full control over your entire environment: reading emails, deleting files, creating new accounts, changing settings. With a regular user account, the damage is much more limited.

What to do: limit admin rights to a maximum of two people. All other employees get a standard user role. It takes five minutes to set up and costs nothing.

Mistake 3: No monitoring of who logs in (and from where)

Did you know that in Microsoft 365, you can see who logs in, from where, and with which device? Most small businesses never look at this. And that's a shame, because this is often the first place where you spot suspicious activity.

Imagine: an employee logs in at 3 AM from Nigeria. That's probably not a business trip. With the right settings, you can automatically block these kinds of sign-ins.

What to do: enable the sign-in logs and review them regularly (or have your IT partner do this). Also consider setting up a policy that only allows logins from Belgium or known devices. Microsoft calls this "Conditional Access" — it's included in most business licences.

Mistake 4: No email security configured

The default spam filter in Microsoft 365 catches most things, but targeted phishing emails regularly slip through. Especially the well-crafted ones — with your bank's logo, an invoice from a supplier, or a supposed message from the accountant.

There are a few settings you can activate yourself that make a big difference:

• Anti-phishing policy: detects attempts to impersonate your domain name
• Safe Links: checks links in emails before you click them
• Safe Attachments: scans attachments in a secure environment before they're opened

These features are included in Microsoft 365 Business Premium — a licence that's worth considering for most small businesses because of the extra security layers.

What to do: check which licence you have and whether these security features are active. In practice, they're often turned off, even if you're paying for them.

Mistake 5: No clear policy for passwords and devices

"Welcome123" or the dog's name with an exclamation mark — we see it daily. And on personal devices with no security whatsoever, people happily work with company data.

That doesn't necessarily have to be a problem, but only if there are ground rules:

• Use strong, unique passwords (or better yet: a password manager)
• Set it up so company data on personal devices can be wiped if an employee leaves or a device is lost
• Make sure devices lock automatically after a few minutes of inactivity

This isn't about distrust. It's about protecting your business and your customers.

What to do: create a simple policy — it doesn't need to be 20 pages. A few clear agreements will do. And communicate them clearly to your team.

Why this matters for small businesses

Large companies have IT departments that handle these things daily. As a small business, you don't have that luxury. But that doesn't mean you have to be more vulnerable.

The five points above don't require a big budget or a technical background. They're basic measures that immediately make your business safer. All you need is someone to look things over with you and adjust the right settings.

Many Belgian businesses assume that Microsoft 365 security is "automatically sorted" once they buy a licence. But that's not the case. Microsoft gives you the tools — it's up to you to actually use them.

Conclusion

Microsoft 365 is a powerful platform, but only when security is properly configured. The five mistakes above are all easy to fix — often in less than an hour.

Want to know how your Microsoft 365 environment stacks up? I'm happy to take a look together. I help small businesses in Hasselt and the surrounding area with setting up and managing their IT securely — practical, personal, and hassle-free.