Article ID: 2727963 - View products that this article applies to.
Not sure what release of Office 365 you're using? Go to the following Microsoft website:
Am I using Office 365 after the service upgrade?
A user can't use his or her email address to sign in to Microsoft Office 365 pre-upgrade or to connect to Office 365 pre-upgrade services.
This issue occurs if user's email address differs from his or her user ID.
To resolve this issue, follow these steps:
This issue can sometimes occur after you transition your company from Microsoft Business Productivity Online Suite (BPOS-S) to Office 365 pre-upgrade.
Still need help? Go to the Office 365 Community
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