How to Securely
Access Shared
Microsoft Files

Microsoft made significant changes to the process of how organizations share files starting in May 2026.

What changed from a Technical Standpoint.

Microsoft began moving all SharePoint Online and OneDrive tenants to Microsoft Entra B2B for external-user authentication. Organizations cannot opt out of this change, and Microsoft controls the rollout timing.

What changed from a non-technical standpoint:

Microsoft changed how external users are authenticated when accessing shared SharePoint and OneDrive content. An external user is someone who does not have a Microsoft account granted by the organization storing the file.

What it means for you:

Now, external users are noticing an "Access Denied" error message when trying to access shared files using the previous verification process. 

This guide explains how to access shared with you from an organization using Microsoft SharePoint or OneDrive.

Before You Begin

There are two things to know before accessing a file or folder shared with you:

1. Which email address was granted access?
   You must verify your identity using the exact email address the file or folder was shared with. 
   Using another email address, even if both addresses belong to you, may result in an Access Denied or Access is Unavailable message.
   
2. Is your email account associated with Microsoft 365?
   Your sign-in process will differ depending on the type of account you use. 

Your experience will depend primarily on whether your email account is associated with a Microsoft 365 environment.

There are emails managed with Microsoft 365 and emails hosted by Non-Microsoft 365 providers.

If your organization uses M365 follow Option 1. If your organization uses one of the other providers, follow Option 2.

Microsoft 365 account: A work or school email account that your organization uses to sign in to Microsoft 365. 
Non-Microsoft 365 account: An email account that is not managed through Microsoft 365. This may include a personal or business email hosted through Google Workspace, Gmail, Yahoo, or another email provider.

Option 1: Your Email is Associated with Microsoft 365

Option 2: Your email is Not Associated with Microsoft

Here's Your Guide to Access SharePoint files as a guest.

Option 1: Your Organization Uses Microsoft 365

If your organization uses Microsoft 365 for your work email, Microsoft will typically authenticate you using your organization's existing Microsoft account and security process. 

Step 1: Open the Sharing Link 

Open the Sharing Link provided by Zelvin Security. When prompted, use the same email address that was granted access. 

Step 2: Select the Correct Microsoft Account

Microsoft may display one or more accounts currently associated with your browser.

Select the work account that matches the email address Zelvin granted access to.

If it isn't displayed, select the option to use another account and enter the correct email address.

Step 3: Sign In 

Enter the password associated with your work account.

Depending on your organization's configuration, Microsoft may redirect you through your company's normal Microsoft sign-in process.

Step 4: Complete MFA

Complete your organization's normal multifactor authentication process.

This may include Microsoft Authenticator or another MFA method used by your organization.

Step 5: Review First-Time Permissions 

The first time you access Zelvin's Microsoft environment, Microsoft may display a permissions or information-sharing screen.

Review the information and accept it to continue.

Step 6: Access the Shared Content 

After your identity has been successfully verified, Microsoft will open the SharePoint file or folder that Zelvin shared with you. 

Option 2: Your Organization Does Not Use Microsoft 365

You do not need a Microsoft 365 subscription to access files Zelvin Security shares with you.

Microsoft can verify an external guest's identity using a one-time passcode sent to the email address that was granted access.

Multifactor authentication is required for external guest access; you will also be required to use Microsoft Authenticator to access Zelvin's shared files.

First-Time Access

The first time you access Zelvin's SharePoint environment, you may need to set up Microsoft Authenticator.

Step 1: Open the Sharing Link 

Open the Sharing Link provided by Zelvin Security. When prompted, use the same email address that was granted access. 

Step 2: Select the Correct Microsoft Account

Microsoft may display one or more accounts currently associated with your browser.

Select the work account that matches the email address Zelvin granted access to.

Step 3: Receive a One-Time Passcode 

Microsoft will send a one-time verification code to the authorized email address.

Check the inbox associated with that email account.

Step 4: Enter the Verification Code 

 Open the email from Microsoft and locate the one-time passcode.

Return to the Microsoft verification screen and enter the code.

Microsoft email one-time passcodes expire, so use the most recently issued code.

Example: Microsoft OTP (one time passcode) email 

Step 5: Set Up Microsoft Authenticator 

Zelvin requires MFA for external guest access, first-time guests who don't already have the required authentication method configured will be prompted to complete additional security setup.

Follow Microsoft's instructions to set up the Microsoft Authenticator app.

You may need to install Microsoft Authenticator on your mobile device if you do not already have it.

Here is what it looks like to complete the Authenticator Setup.

Step 6: Confirm Authentication

Complete the Microsoft Authenticator approval or verification requested on your device.

Once authentication is successful, Microsoft should complete your guest sign-in.

Step 7: Access the Shared Content 

After successful authentication, the SharePoint file or folder shared by Zelvin should open.