Sync issue with an old disabled email address

Question

Sync issue with an old disabled email address

Jaime Catbagan 0

We created a new AD account, but the email address of this new user is still in Microsoft Entra ID and creating a sync issue when reusing the same email address. How do I fix that?

Rukmini 36,775 Reputation points Microsoft External Staff Moderator

2026-03-18T20:36:59.7933333+00:00
Hey Jaime Catbagan As discussed over private messages, the issue is resolved and you were able to delete the old account in Entra ID and use the same old email address.

it sounds like the old disabled account (and its proxyAddresses) is still hanging around in your Entra tenant, so when you try to sync a new on-premises user with the same email, Azure AD sees it as a duplicate and blocks the change. You can clear that up in a couple of ways:

Permanently delete the old object so the address is released

In the Azure portal go to Entra ID > Users > Deleted users, find the soft-deleted account, and choose Permanently delete.

Or use PowerShell:
Connect-AzureAD $old = Get-AzureADUser -All $true -Filter "mail eq '******@domain.com'" -IncludeDeleted Remove-AzureADUser -ObjectId $old.ObjectId -RemoveFromRecycleBin

Run a delta sync:
Import-Module ADSync Start-ADSyncSyncCycle -PolicyType Delta

If you still need to keep the old object, strip out the conflicting proxyAddresses attribute

Edit the on-premises AD user (or Azure AD object if it hasn’t fully deleted) and remove the old smtp: entries from the proxyAddresses attribute.

Let AD Connect sync those attribute changes back up.

After you’ve either hard-deleted the old object or cleaned up its proxyAddresses, kick off another sync and the new user should come across with that email successfully.

Note: This content was drafted with the help of an AI system. Please verify the information before relying on it for decision-making.