Issues with External Collaboration in Microsoft Teams

Question

Issues with External Collaboration in Microsoft Teams

Daniel 86

I have a question about MS Teams external collaboration.

When an employee from our M365 tenant is invited to join an external Microsoft Team or Teams channel using their primary SMTP address, it is not being recognized or mapped to their Microsoft work account within our company tenant. This results in authentication issues for the users when attempting to access external Microsoft Teams resources to which they’ve been invited.

However, when they are invited using their UPN (SMTP that matches their UPN), this issue does not occur. External organizations are generally unaware of our UPNs and therefore default to using the primary email address to extend invitations.

This unexpected behavior disrupts normal business operations and hampers collaboration with external partners and clients, making it necessary to address and resolve this issue.

Has anyone encountered this situation and found a solution?

JimmyYang-MSFT 58,646 Reputation points Moderator

2024-10-29T09:47:22.3333333+00:00
@Daniel

It sounds like you're encountering an issue where the primary SMTP address isn't properly recognized for authentication when users from your Microsoft 365 (M365) tenant are invited to external Microsoft Teams. However, when the User Principal Name (UPN) matches the SMTP address, the authentication process works seamlessly. Here are a few steps and suggestions that might help resolve the issue:

Verify SMTP and UPN Alignment: Confirm that the SMTP addresses and UPNs for users in your tenant are aligned. Misalignment between these can often cause authentication issues.

Azure AD Configuration: Check the configurations in Azure Active Directory (AAD) for any discrepancies or misconfigurations that might affect authentication. Ensure that users' email addresses are correctly configured in AAD.

Guest Access Settings: Review the guest access settings in both your M365 tenant and the external tenants. Make sure that the external tenant is allowing guest access and that there are no restrictive policies that could interfere with authentication.

Communication with External Organizations: Since external organizations generally are not aware of your UPNs, consider communicating the importance of using the UPN for invitations, if feasible. You could provide a guide or a template to them explaining how to invite users properly.

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JimmyYang-MSFT 58,646 Reputation points Moderator

2024-10-29T09:47:22.3333333+00:00

@Daniel

It sounds like you're encountering an issue where the primary SMTP address isn't properly recognized for authentication when users from your Microsoft 365 (M365) tenant are invited to external Microsoft Teams. However, when the User Principal Name (UPN) matches the SMTP address, the authentication process works seamlessly. Here are a few steps and suggestions that might help resolve the issue:

Verify SMTP and UPN Alignment: Confirm that the SMTP addresses and UPNs for users in your tenant are aligned. Misalignment between these can often cause authentication issues.

Azure AD Configuration: Check the configurations in Azure Active Directory (AAD) for any discrepancies or misconfigurations that might affect authentication. Ensure that users' email addresses are correctly configured in AAD.

Guest Access Settings: Review the guest access settings in both your M365 tenant and the external tenants. Make sure that the external tenant is allowing guest access and that there are no restrictive policies that could interfere with authentication.

Communication with External Organizations: Since external organizations generally are not aware of your UPNs, consider communicating the importance of using the UPN for invitations, if feasible. You could provide a guide or a template to them explaining how to invite users properly.

Answer 1

Hello,

SMTP and UPN are different. User has UPN ******@doman.eu and SMTP is ******@domain.com. When users are being invited to different organization this works fine except for one organization. I have tried to recreate the issue with a test tenant and I'm not able to do so.
Azure AD part is fine
In our tenant there are no special settings that would prevent guest access to work.
That is an option, but I would like to know why it works in 99,9% of the cases and it doesn't work in 0,1%.

Any hint idea where to look and what to change configuration vise on my test tenant to replicate the issue will be more then welcome.

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Issues with External Collaboration in Microsoft Teams

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