Consider the following scenario:

  • You configure a federation trust between two organizations by using Microsoft Federation Gateway.

  • The first organization is a mixed Exchange Server 2003 and Exchange Server 2010 environment.

  • The second organization is an Exchange Server 2010 only environment.

  • A user in the second organization looks up the free/busy information of an Exchange Server 2003 mailbox user in the first organization.

In this scenario, hash marks are displayed instead of the Free/Busy information.

When Exchange 2010 in the remote organization detects an autodiscover query being performed for a legacy Exchange 2003 mailbox, Exchange 2010 will fail the lookup because Exchange 2003 does not support Autodiscover.


To resolve this issue, install the following update rollup:

2579150 Description of Update Rollup 4 for Exchange Server 2010 Service Pack 1

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

A separate issue with Exchange 2003 Cross-Org lookups has been identified due to MergedOnly Free/Busy information being returned. For more information , click the following article number to view the article in the Microsoft Knowledge Base:

2567863 Free/Busy information may not be returned when a Cross-Org query is performed from a legacy Exchange user


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