This article will show you how to create a new Azure AD directory using a custom domain using the Microsoft Azure Portal.
Using a custom login domain, I’ll not going to use the Microsoft Azure default directory UPN which Is email@example.com Instead I’ll use firstname.lastname@example.org as my UPN.
To do this I’ll use the old Azure portal and not the new as this feature Is only available on the old portal.
To start, I’ll Login to the portal https://manage.windowsazure.com -> Active Directory -> New
Directory -> Custom Create
In the Add directory I Select Create new directory and fill In all the details
Next I click on the newly created directory
Next I’ll add a custom domain that will allow me to log on using email@example.com
I Click on Add Domain
In the domain name I type the domain name
Next I will add a TXT record to my DNS zone that will verify the ownership
Once the domain Is verified the status will show Verified
To add users click on users -> Add
As you can see I use my domain now to create login UPN.
When a user try to log for the first time he will need to change his password