Keep in mind there's a rough limit of about 1300 values stored in there. In order to add a UPN suffix to your Active Directory you use Active Directory Domains and Trusts, right-click the root node and select Properties. When more than two Forest reside in the same DNS namespace, and the root of that DNS tree is also an Active Directory forest, logic must be added to the Name Suffix Route to ensure authentication traffic is routed to the correct forest root. To add a UPN suffix to the on-premises Active Directory in the event that the Active Directory domain uses a non-routable namespace, perform the following steps: Open the Active Directory Domains And Trust console and select Active Directory Domains And Trusts. Then choose Active Directory Domains and Trusts. All can login without issues. Assign the suffix to a user account On the UPN Suffixes tab, enter the suffix to add 1 and click Add 2. Add a UPN suffix Open the Active Directory Domain and Approvals console. For example: user1@contoso.com. Beforehand, you need to add System.DirectoryServices.dll to your project (Project menu -> Add Reference -> .Net tab). For example, if your logon name is administrator@ad.contoso.com, the part of the name to the right of the ampersand is known as the UPN suffix (so, in this case A User Principal Name ( UPN ) is made up of two parts, the prefix (user account name) and the suffix (DNS domain name). Return to Top How To Add & Remove UPN Suffix Quick & Simple.See documented video and more on http://www.arondmessaging.ro/ Learn all about User Principal Name (UPN) suffixes and how to add additional UPN suffixes to Active Directory in this helpful Ask an Admin article. Thank you, we already have the domain.com in place, attempting to make it the default when creating users to reduce potential for future errors when creating new users. 3, The user could log on with aa@hotmail.com. The UPN suffix is added, click on Apply 1 and OK 2 to close the properties. Change UPN Suffix for Existing Users. Open Active Directory Domains and Trusts On the left hand side of the new window, right click on Active Directory Domains and Trusts, and select Properties (as shown below). Active Directory Domains and Trusts Window Type in your new domain suffix in to the Alternative UPN suffixes box, and then click Add. Now head over to the Active Directory users and Computers. In the left pane, right-click Active Directory Domains and Trusts and then choose Properties. It will open Active Directory Users and Open Server Manager using the icon on the desktop taskbar, or from the Start screen. You should verify the domains (also known as UPN suffixes) that are used in Azure AD before the users are synchronized. 2. The attribute userPrincipalName is the attribute that users use when they sign in to Azure AD and Office 365. Once you done that, close and reopen the ADUC and when you are creating a new user you should be able to select the new UPN suffix for that account. On the UPN Suffixes tab, enter Specify our Public Domain (SharePointChronicle.com) here. On the left hand side of the new window, right click on Active Directory You can change a user's UPN in the Microsoft 365 admin center by changing the user's username or by setting a different email. UPN suffix routing must be configured in Active Directory environments where trust relationships exist between drills. Routing of UPN suffixes is not available with external approvals (between domains), in this case users will have to use their DOMAIN\user identifier. You need to modify the upnSuffixes attribute of the CN=Partitions,CN=Configuration,DC=ForestRootDomain,DC=com object. We strongly recommend that you keep the default attribute userPrincipalName. Right-click the Active Directory Domains and Trusts icon and select Properties. Currently both the .com and the .local are present in the drop down under create new user, but the .local is the default selection. Changing the User Principal Name (UPN) in Active Directory You can display the current value of the UserPrincipalName attribute using the Get-ADUser cmdlet: Get-ADUser f.martusciello -properties select userprincipalname In the UPN Suffixes tab, type an alternative UPN suffix (such as sales.example.com). The following is C# Code sample to retrieve the UPN Suffixes from Active Directory. Adding a UPN Suffix to Active Directory But it is easier to use PowerShell to change the user UPN suffix. To change a UPN suffix for a user, use the Set-ADUser cmdlet with the UserPrincipalName parameter: The following PowerShell script allows to find users with the specific UPN suffix in an OU and change the UserPrincipalName to a new one. Select Active directory domain and trusts from the server hosting active directory. Search for: Search Sections Right click the root and select Properties. Select Active Directory Domains and Trusts from the Tools menu. Add the alternative UPN suffixes, for example, hotmail.com. Right click on Active Directory Domains and Trusts 1 and click Properties 2. On the UPN Suffix tab, enter the UPN Suffix in Alternative UPN Suffixes, select ADD, for an example here I had added (anandpnair.com) as an alternative UPN suffix Once it's added you can see the UPN suffix in the box click on Apply and OK to finish to add the alternative UPN Suffix successfully Click Add or Remove, and then click OK. 1, Open the AD Domains and Trusts, click the AD Domains and Trusts and choose "Properties". On the Active Directory Domains and Trusts window, right-click Active Directory Domains and Trusts, and then choose Properties. This video show you how to add UPN suffixes to a Active directory forest. In the left pane, you should right-click in the Active Directory Domain and The domain names I would like to add as UPN Suffixes are verified as Custom Domains in Azure AD. The UPN name is unique in the forest. UPN suffixes form part of Active Directory (AD) logon names. Insufficient access rights to perform the operation" I am signed into a AAD DS joined server and using an AAD DS administrator account in the group "AAD DC Administrators". In this case, the prefix is "user1" and the suffix is "contoso.com." On the Action menu, click Properties. In this Ask an Admin, Ill explain what User Principal Name (UPN) suffixes are and how to add them to your Active Directory infrastructure. This will open up the window where we can specify the UPN Suffix. To do that, you can go into Active directory Domain and Trust then right click on ADDT and select properties > Select UPN suffix > and enter your new UPN suffix and click add. Click on Add. Here you add your additional UPN suffix which, in our example is the same as the external domain we added and verified on our Azure portal. using System.DirectoryServices; We tested this and it looks good. Right-click Active Directory Domains and Trusts in the left navigation pane, and select Properties from the context menu: Type the new UPN suffix that you would like to add to the Active Directory forest, select the UPN suffix that you would like to remove, or simply glance over the list of UPN suffixes. 2, Then configure the User logon name as shown below. 1. Open Server Manager using the icon on the desktop taskbar, or from the Start screen. You can also add a UPN suffix. These steps will put the public domain in AD, if you are using a .local or something similar. On the Active Directory Domains and Trusts window, right-click Active Directory Domains and Trusts, and then choose Properties. On the UPN Suffixes tab, in the Alternative UPN Suffixes box, type your new UPN suffix, and then choose Add. Click OK when finished. The alternative UPN suffix is added successfully. Step 1: Add the new UPN suffix On the AD DS domain controller, in the Server Manager choose Tools > Active Directory Domains and Trusts. This can be accomplished by adding Exclusions to the Name Suffix Routes. Open the Active Directory Domains and Trusts properties; Add a new suffix to the Alternative UPN suffixes box and click Add. 3. New users (with new upns) are synced. Something like this should work - just wrote the code in the textbox though so might need a bit of tweaking: "Windows cannot update the UPN suffixes. These, however, are immediate results so you may want to do some more thorough testing. ___Add the public email domain as an Alternative UPN Suffix ___Open Active Directory Users and Computers ___Change all users UPN suffix to the Public UPN Suffix ___Type in each users email in the email location. Open AD Domains and trusts >> Right click on Active Directory Domains and Trusts and select properties. Choose Add and then choose Apply. Open Active Directory Domains and Trusts. So if you go to the account tab of a user in ADUC you will see the "User Logon Name" that is the first box then the @domainname >> that is the UPN suffix. To add a new UPN suffix to a Windows Server 2003 domain: 1. Adding a UPN Suffix to Active Directory Log in to Windows Server with a domain administrator account. For the uPNSuffixes you need to have Domain Administrator Privileges in order to load them up in the property cache. Users with updated upns are too.