Article summary: Guest accounts and external sharing permissions can accumulate over time as employees collaborate with vendors, clients, and contractors. Regularly reviewing access in Microsoft Teams and SharePoint helps businesses identify who can access company data, confirm whether that access is still necessary, and remove permissions that are no longer needed. With the right controls in place, businesses can collaborate securely without allowing outdated access to linger.
A contractor finishes a project in March. Six months later, their guest account still has access to the project’s SharePoint folder and Teams channel, including files added long after their work ended.
No one intentionally left the door open. The account simply fell through the cracks.
External access is easy to grant in Microsoft Teams and SharePoint, but it is just as important to know when that access should end. Without a process for reviewing guest accounts and shared resources, temporary access can quietly become permanent.
That is why collaboration security should include regular reviews of external sharing permissions. It is a simple step that helps ensure contractors, vendors, and other guests can only access business data for as long as they need it.
Why External Sharing Permissions Quietly Pile Up
External access usually starts for a good reason. A contractor joins a project, a vendor needs a folder, or a client is invited into a Team.
The problem is that access can remain long after the work is finished. As people and projects come and go, old guest accounts and sharing permissions can easily be forgotten.
Microsoft recommends regularly reviewing guest access so organizations can confirm who still needs it and remove access that is no longer necessary.
Nothing has to go wrong for this to become a security risk. Without regular reviews, legitimate access can simply stay in place longer than it should.
The Change Making This More Important
Microsoft is changing how external sharing works in SharePoint and OneDrive.
Starting in May 2026, Microsoft began moving all tenants to Microsoft Entra B2B for external sharing. Instead of managing some external users through SharePoint alone, invited guests are represented in the organization’s Microsoft Entra directory.
That gives businesses more consistent control over external users, but it also makes guest account management more important. As Microsoft recommends, organizations should have a process for reviewing external users and removing those who no longer need access.
For small businesses, the takeaway is simple: external access should no longer be something you grant once and forget. Someone needs to know who your guests are, what they can access, and when that access should end.
Auditing External Sharing Permissions in Teams and SharePoint
A good external access review starts with a simple question: who outside your business can access your Microsoft 365 environment, and do they still need that access?
Review Your Guest Accounts
Start with the guest users in Microsoft Entra. Look for former contractors, vendors, clients, and other external users whose work with your business has ended.
Microsoft recommends regularly reviewing guest access and removing access when there is no longer a legitimate business need.
Review SharePoint Sharing
Next, look at what has been shared outside your organization. SharePoint provides sharing reports that can help site administrators identify files and folders shared with guests.
Pay particular attention to older project sites and other locations that may no longer have an active owner keeping an eye on access.
Check Teams Guest Membership
Review the guest members of each Team, particularly Teams created for temporary projects or outside collaboration.
Guests can access standard channels and their files as long as they remain members of the Team. Removing someone from a Team does not automatically remove their guest account from your organization’s directory.
Set Guardrails for Future Sharing
Cleaning up old access solves only half the problem. Businesses also need rules that prevent unnecessary access from accumulating again.
Microsoft 365 provides controls that can help, including guest access expiration and domain restrictions. Businesses can also limit anonymous links, set expiration periods for them, or make more restrictive sharing options the default.
These controls matter for more than cybersecurity. Under PIPEDA, organizations remain accountable for personal information transferred to third parties for processing.
The goal is not to stop employees from collaborating outside the business. It is to make sure external access is intentional, limited, and removed when it is no longer needed.
That approach also aligns with the Canadian Centre for Cyber Security’s defence-in-depth guidance: use multiple security controls together rather than depending on a single setting to protect business data.
Not Sure Who Still Has Access to Your Files?
You probably know which vendors, contractors, and clients your business works with today. But do you know who still has access to your Teams channels, SharePoint sites, and shared files?
A review of external sharing permissions can uncover outdated guest accounts, unnecessary access, and sharing settings that no longer match how your business operates.
Regular access reviews also make it easier to keep external collaboration secure without making it harder for employees to work with the people they need.
Data First Solutions can help you review your Microsoft 365 environment and strengthen how external access is managed. Call our sales team at 416-412-0576 or reach us online to book an assessment.
Article FAQs
What counts as external sharing in Microsoft 365?
External sharing occurs when someone outside your organization is given access to Microsoft 365 resources. This can include adding guests to Teams or SharePoint or sharing files and folders with external users.
How can I find out who has access to our SharePoint sites?
SharePoint administrators and site owners can use sharing reports to review externally shared content and guest access. Businesses should also review guest accounts in Microsoft Entra to get a broader picture of who has access across the organization.
What is changing with Microsoft’s one-time passcode sharing?
Microsoft is moving SharePoint and OneDrive external sharing to Microsoft Entra B2B. External users are managed as guests through Microsoft Entra, providing a more consistent way to manage and review access. Email one-time passcodes can still be used to authenticate guests who do not have another supported account.
