What is a User Principal Name (UPN) in Microsoft 365?

A User Principal Name (UPN) is the unique identifier assigned to a user in Microsoft 365. It’s primarily used for user sign-in to access Microsoft services like Teams, Outlook, and SharePoint. A UPN takes the form of an email address, combining a username with a domain name, such as: username@domain.com.

Key Characteristics of a UPN

1. Globally Unique :
   Each UPN must be unique within the tenant to avoid conflicts.
2. Format:
   
   • Username: Typically derived from the user’s name or employee ID.
   • Domain: Can be the default tenant domain (e.g., companyname.onmicrosoft.com) or a verified custom domain (e.g., companyname.com).
3. Purpose: : A UPN is essential for:
• Authentication and single sign-on (SSO).
• Synchronizing user identities across hybrid environments.

How UPN Differs from Email Address

Although a UPN often matches a user’s email address, they can be different. The UPN is used for sign-in purposes, while the email address is used for communication. For example:

• UPN: jdoe@companyname.com
• Email: john.doe@companyname.com

Common Use Cases

• User Sign-In: Allows seamless authentication across Microsoft 365 services.
• Hybrid Identity: Links on-premises and cloud accounts in hybrid setups.
• Automation: Used in PowerShell scripts for managing user accounts.

The UPN plays a vital role in identity management within Microsoft 365, ensuring secure and efficient access for users. 🚀

Explore More

1. Using UserPrincipalName to fetch User Details in Graph PowerShell