This is due to the Microsoft Online Email Routing Address (MOERA). The MOERA is constructed from the person's userPrincipalName attribute in Active Directory and is automatically assigned to the cloud account during the initial sync and once created, it can't be modified or removed in Microsoft 365. Later, you can change the username in the Active Directory, but it doesn't change the MOERA and you might run into issues displaying the newly changed name in the Global Address List., User Lookup Get detailed information about Discord users with creation date, profile picture, banner and badges. Guild Lookup Get detailed information about Discord guilds with creation date, Invite/Vanity URL, features and emojis., This will show you all User IDs of the computer whether Microsoft account or Local accounts. If you are not logged in, then your current user ID will be shown on left bottom side. You can click on Other Users to see other IDs as well. Do let me know if you have any more question or require further help..