Bulk Updating UPN’s

As part of a recent project I had to migrate 1500 user objects between two AD domains and then sync them with Azure AD – I’ll cover that entire project and its challenges, of which there was a handful in another post.

As part of that migration, I needed to bulk update the UPN’s of the newly created accounts to align with the custom domain name configured in Azure AD, that begs the question why didn’t I just stand up the new AD domain with the appropriate suffix in the first instance, and the honest answer is this project was extremely fast-moving and we had to make decisions on the fly whilst we were working on the strategic architecture, again, this will become clearer when I cover the project in more depth.

Anyway, with 1500 user objects to update I certainly wasn’t doing that manually, I used the below script to target all users in a specific OU and change their UPN.

Note, if you are to use this please ensure you have created the new UPN in AD Domains and Trusts first, details on how to do that here.

Import-Module ActiveDirectory

$oldSuffix = "oldsuffix.local"
$newSuffix = "newsuffix.co.uk"
$ou = "OU=New-Accounts,DC=oldsuffix,DC=local"

Get-ADUser -SearchBase $ou -filter * | ForEach-Object {
$newUpn = $_.UserPrincipalName.Replace($oldSuffix,$newSuffix)
$_ | Set-ADUser -UserPrincipalName $newUpn
}