Why certain UPN is not valid Microsoft user name?

[s168635]

I have a user email address showed in my report user list with "Read" access:

But she could not sign on using the email address:

This is confusing, how can she reach the report showed she has access? What would be her Microsoft Account?

Thanks for your help,

Bo

[GilbertQ]

Hi there

I would contact your admin to verify the account details.

[s168635]

It is not my ADMIN.

I have a report shared with many external users out side my org, the situation happens a lot: user was granted access but they do have UPN other than their primary email, which is ok for me, but, as the screen shot shows: the email is not a valid Microsoft account.

So my question is, why Microsoft allow this to happen? If you know user's email, you should allow user to sign on with it, otherwise, what's the purpose showing user has such email address?

Bo