Forum Discussion
Help: AzureAD B2B Error Message: Multiple users contain this email address.
Problem Description:
As documented in this feedback (see link text below) Azure AD B2B has a problem for all users accounts where Live ID signin name and Office 365 signin name are the same:
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I've just resolved the same issue.
In this case it was caused by a contact having the same SMTP address as the user trying to sign in. Obviously the resolver asked for the account associated with the smtp and couldn't decide.
It was a little tricky to find as different searches in different admin consoled didn't show the interloper. In the end searching the main portal.office.com active users for the first part of the email found the user with a comlicated username of a_user#EXT#@.....onmicrosoft.com - removing this fixed it. Oddly in the exchange admin it didnt' appear in users but in contacts.
It can then be deleted from the portal (either office or azure)
Worked for me.