Post-M365 Migration: Authentication & Teams Document Access Issues with External Customers

Question

After migrating to Microsoft 365, many of our employees encountered issues authenticating or accessing Teams documents shared by third-party customers. Before the migration, some employees created "Personal" 365 accounts using our company email addresses. Post-migration, these users lost access to Teams set up by our customers, despite attempts by customers to delete and re-invite them.

Is there a way to reset security or authorization tokens for affected users without creating new email addresses for each employee?

Answer 1

Hi @Trevor Perry

According to your case description, you need to grant these "personal accounts" access to Teams documents. There are some ways to grant external customers access to Teams documents without creating a new email address for each employee:

1. Use a shared link: You can generate a shared link and set it to "Anyone can access". In this way, external customers can access the document without logging in. However, this method is less secure and is suitable for non-sensitive files.
2. Guest access: With the guest access feature of Microsoft Teams, you can invite external customers to join your team as guest users. They can use their email address to authenticate and access shared documents. Please refer to: https://learn.microsoft.com/en-us/microsoftteams/guest-access.
3. Microsoft Entra B2B collaboration: With Microsoft Entra B2B collaboration, you can set conditional access and multi-factor authentication (MFA) policies for external users to ensure that they can access shared resources securely. Please refer to: https://learn.microsoft.com/en-us/entra/external-id/authentication-conditional-access.
4. Shared folder: Create a shared folder in OneDrive or SharePoint and send its link to external customers. You can set access permissions to ensure that only specific external customers can access the folder.

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