In an Exchange 2003 and Office 365 Hybrid Deployment environment, the Office 365 users are able to view the Free/Busy information of Exchange 2003 users or resources. However, the Exchange 2003 user may not be able to view the Free/Busy information of the Office 365 users or resources unexpectedly.


Many configuration issues may result in the issue mentioned in the symptoms. Below two issues are observed in the business environment:

Issue 1

The primary proxy address may not be configured correctly.

How to identify this issue

From the network trace, you will see the following information when the Exchange 2003 users queries Free/Busy information of the Office 365 users or resources:


ADProvider FederatedIdentity Could not find a SMTP proxy address corresponding to a federated accepted domain for user <domain>/Users/FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042


How solve this issue

Use the Set-Mailbox cmdlet to correct the primary SMTP proxy. A sample is listed below:


Set-Mailbox -Identity FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042 -Arbitration -EmailAddresses FederatedEmail.4c1f4d8b-8179-4148-93bf-00a95fa1e042@<domain>


More information about the Set-Mailbox cmdlet


Issue 2

The permission for the related Free/Busy folder may not be configured correctly. For example the permission for External (FYDIBOHF25SPDLT) Free & Busy folder is incorrect



Default permission: Author



Default permission: Editor


More Information


Applies To

Exchange Server 2003

Exchange Server 2010

Office 365 for enterprises