Intro

In Active Directory, the User Principal Name (UPN) attribute is a user identifier for logging in, separate from a Windows domain login. For more, see Microsoft's User Naming Attributes

It has the format of an email address (eg: rogercruz@example.com).

Documentation

• User Naming Attributes

• Active Directory Domain Services

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Tips and Tidbits

• A UPN consists of a UPN prefix (the user account name) and a UPN suffix (a DNS domain name). The prefix is joined with the suffix using the "@" symbol.

• A UPN must be unique among all security principal objects within a directory forest.