Microsoft 365 has become the lifeline for small and midsized businesses. It’s where your email lives, your files are stored, and your team collaborates every single day. From Outlook and Teams to SharePoint and OneDrive, it’s a full ecosystem that keeps work moving.
The problem? Most businesses assume Microsoft handles security, backups, and compliance automatically. That assumption can lead to serious vulnerabilities. Microsoft provides the platform, but you, the customer, are responsible for your data, your access policies, and your configurations.
At ALCO USA Inc., we’ve conducted dozens of Microsoft 365 security audits for companies of every size — and nearly every one had overlooked the same few issues. These problems are easy to miss, but costly if ignored. Here are five of the most common risks small businesses overlook in Microsoft 365.
Weak or Shared Admin Accounts
– Too often, we find businesses sharing one global admin account between multiple staff members or IT vendors. It may feel convenient, but it’s extremely dangerous. Shared credentials eliminate accountability — if something changes or is compromised, there’s no way to trace who did it. Every administrator should have their own unique login secured with multi-factor authentication (MFA). We recommend reviewing admin roles quarterly to confirm only the right people have elevated access.
Inactive Mailboxes That Still Receive Mail
– When an employee leaves, their account often remains active “just in case.” Those mailboxes still receive emails and attachments — and may still sync to old devices or be targeted by phishing attempts. We’ve seen cases where old mailboxes were used by hackers to impersonate former employees. At ALCO, we implement mailbox retention policies, forwarding rules, and timed deactivations to keep data safe without losing important communications.
Files Shared Publicly Without Realizing It
– One of the most common surprises during our audits comes from SharePoint and OneDrive sharing links. Many users click “Anyone with the link” when sending files, unaware this makes documents public on the internet. Over time, thousands of files can accumulate with open access. These links are often indexed by search engines and can expose sensitive information like invoices or contracts. A simple permissions audit can reveal which files are shared externally and help lock them down securely.
No Backup or Retention Policy
– Microsoft 365 offers built-in versioning and short-term retention, but it’s not a true backup solution. Once data is deleted and retention periods expire, it’s gone for good. Many businesses discover this too late — after a ransomware attack, a disgruntled employee, or simple human error. ALCO deploys third-party, cloud-to-cloud backup systems for Exchange, SharePoint, and Teams. This ensures every version of your data is safe, recoverable, and compliant with business continuity standards.
MFA Exceptions for Executives
– This one surprises people the most. Executives are frequently excluded from MFA because they “don’t want the hassle.” Unfortunately, hackers target these accounts first — they know senior staff have access to financial data, contracts, and confidential communications. In every breach we’ve seen involving Microsoft 365, MFA exceptions were part of the problem. Implementing conditional access rules and enforcing MFA across all accounts is one of the simplest, most powerful steps you can take to protect your business.
How ALCO USA Helps
Our Microsoft 365 Security Assessment process is built around one goal: to give you complete visibility and control over your environment. We identify misconfigurations, insecure sharing practices, and compliance gaps, then correct them — often within a single working day.
We also help organizations implement long-term solutions: automated backups, identity protection, retention policies, and security baselines that evolve as your company grows. It’s not about adding more complexity — it’s about simplifying and securing what you already have.
If you’re unsure how your Microsoft 365 environment is configured or whether your data is fully protected, ALCO can help. We offer a free preliminary assessment to identify risks before they become real problems.
The bottom line: Microsoft 365 is one of the most powerful business platforms available, but it’s only as secure as the team managing it. Let’s make sure yours is airtight.
