MC1187400 - Syncing HiddenFromAddressListEnabled attribute across tenants for consistent Global Address List (GAL) visibility

Introduction

We are improving People Search in the Global Address List to correctly handle the HideFromAddressListEnabled attribute. Previously, when users were synced across tenants via Entra Cross Tenant Sync, this attribute did not propagate, causing hidden users in the source tenant to appear in the target tenant’s Global Address List (GAL). 

With this update, the attribute will sync across Exchange and Entra directories, and a backfill process will ensure previously synced users reflect the correct visibility. Dual write ensures all future sync operations propagate HideFromAddressListEnabled correctly

When this will happen:

• General Availability (Worldwide, GCC, GCCH, and DoD): We will begin rolling out late November 2025 and expect to complete by mid-December 2025.
• The update will run automatically in the background and may take several weeks to complete, depending on tenant size.

How this affects your organization:

• Who is affected: Admins managing Entra Cross-Tenant Sync and Exchange Online environments; organizations with users hidden from GAL in the source tenant.
• What will happen:
  • Tenant Admins:
    • No manual action is required for the update.
    • After completion, synced external users will have consistent visibility settings across tenants.
  • Users:
    • Users hidden in the source tenant will now be hidden in the target GAL.
    • No impact on sign-in or collaboration features. 

What you can do to prepare:

• Review any custom scripts or workflows that rely on GAL visibility and update if needed.
• Communicate to helpdesk teams that visibility changes may occur for previously synced users.
• Optional: Use PowerShell to verify visibility after the update:

  Get-MailUser -Identity <UserPrincipalName> | Select HideFromAddressListEnabled

• No changes are required to Cross-Tenant Sync configuration.

Compliance considerations:

No compliance considerations identified, review as appropriate for your organization.

FAQ

• Q1: Will this impact mail flow or message delivery?
  No. This change only affects GAL visibility and does not impact mail routing or delivery.
• Q2: Do I need to reconfigure Cross-Tenant Sync settings?
  No. The update is automatic and requires no configuration changes.
• Q3: How long will the update take?
  Duration depends on tenant size. It runs in the background and does not disrupt service.
• Q4: Can I monitor progress?
  Currently, there is no admin-facing progress tracker. You can verify individual users with PowerShell after completion.
• Q5: Will new users synced after this update require special handling?
  No. Dual-write ensures all future sync operations propagate HiddenFromAddressListEnabled correctly.