Set a domain alias for every user in Microsoft 365

Sometimes, we add a new domain to Microsoft 365 and we want to have a domain alias for multiple or every user.

Logging in Exchange Online Powershell

To configure a alias for every user, we need to login into Exchange Online Powershell:

Connect-ExchangeOnline

If you don’t have the module already installed on your computer, run the following command on an elevated window:

Install-Module ExchangeOnlineManagement

Source: https://www.powershellgallery.com/packages/ExchangeOnlineManagement/3.7.2

Adding the 365 domain alias to every user

After succesfully logged in, run the following command:

$users=Get-Mailbox | Where-Object{$_.PrimarySMTPAddress -match "justinverstijnen.nl"}

Here our current domain is “justinverstijnen.nl” but let’s say that we want to add “justinverstijnen.com”. Run the following command to do this:

foreach($user in $users){Set-Mailbox $user.PrimarySmtpAddress -EmailAddresses @{add="$($user.Alias)@justinverstijnen.com"}}

Now we have added the alias to every user. To check if everything is configured correctly, run the following command:

$users | ft PrimarySmtpAddress, EmailAddresses

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