Azure Active Directory - Link
Microsoft Tech Community -
Azure Active Directory - Link
Official Blog
Azure AD - Link
What's New -
Azure Active Directory - Link
Azure Active Directory Comparison - Link
Azure Active Directory - Introduction (Wiki) - Link
Configuring Alternate Login ID - Link
When your UPN can't match the user login ID.
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Azure AD Premium P1
Included in E3 Enterprise Mobility + Security
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Azure AD Premium P2
Included in E5 Enterprise Mobility + Security
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