Issues with External Collaboration in Microsoft Teams

Daniel 86 Reputation points
2024-10-28T13:03:53.49+00:00

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?

Microsoft Teams | Microsoft Teams for business | Other
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  1. Daniel 86 Reputation points
    2024-11-29T10:53:54.01+00:00

    Hello,

    1. 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.
    2. Azure AD part is fine
    3. In our tenant there are no special settings that would prevent guest access to work.
    4. 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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