"The e-mail address could not be resolved to an ExchangePrincipal" error when a user tries to view free/busy information in Outlook

Consider the following scenario:

• The mailbox for User 1 is hosted on Microsoft Exchange Server 2007.
• User 1 is running Microsoft Outlook 2010.
• User 1 enables the "Enable troubleshooting logging" option in Outlook 2010.
• User 1 views the free/busy information for User 2.
• The mailbox for User 2 is hosted on Microsoft Exchange Server 2010.
• The server that is running Exchange Server 2010 is removed from a Database Availability Group (DAG).
• The mailbox for User 2 is moved to a different server that is running Exchange Server 2010.
• User 1 tries to view the free/busy information for User 2.

In this scenario, User 1 cannot view the free/busy information for User 2. Additionally, an error message that resembles the following is logged in the Availability Service log file:

<FreeBusyResponse><ResponseMessage ResponseClass="Error"><MessageText>The e-mail address &lt;domain
User&gt;SMTP:user@contoso.com could not be resolved to an ExchangePrincipal object.</MessageText><ResponseCode>ErrorMailRecipientNotFound</ResponseCode><DescriptiveLinkKey>0</DescriptiveLinkKey>
<MessageXml><ExceptionType xmlns="http://schemas.microsoft.com/exchange/services/2006/errors">Microsoft.Exchange.InfoWorker.Common.Availability.MailRecipientNotFoundException</ExceptionType><ExceptionCode
xmlns="http://schemas.microsoft.com/exchange/services/2006/errors">5009</ExceptionCode></MessageXml></ResponseMessage>

This issue occurs because the msExchHomeServerName attribute in Active Directory Domain Services (AD DS) is not valid for the user whose mailbox was moved.

To resolve this issue, use one of the following methods:

Method 1: Update the msExchHomeServerName value for the user

To resolve this issue, update the msExchHomeServerName value for the user whose mailbox was moved. To do this, follow these steps:

1. Start Active Directory Service Interfaces (ADSI) Edit.
2. Expand Default Naming Context (servername), and then expand DC=domain, DC=com.
3. Click Users.
4. Right-click the user whom you want, and then click Properties.
5. Under Attribute, click msExchHomeServerName, and then click Edit.
6. Click Clear, use a copy and paste operation or type the legacyExchangeDN of the new mailbox server name, and then click OK. For example, type the following:
   
   /o=EXORG/ou=Exchange Administrative Group (exchange_group_name)/cn=Configuration/cn=Servers/cn=mailbox_server_name
   
   Note We recommend that you copy and paste the legacyExchangeDN from a different mailbox on the same server to avoid any errors.
7. Exit ADSI Edit.

Method 2: Run the Get-ADUser cmdlet

To resolve this issue, run the Get-ADUser cmdlet. To do this, at a command prompt, type the following command, and then press Enter:Note The Get-ADUser cmdlet is available in Windows Server 2008 R2 and later versions when you run the Import-Module ActiveDirectory command.

Exchange Server 2007 queries AD DS for the msExchHomeServerName value to determine the location of the mailbox and the Client Access server (CAS).The msExchHomeServerName attribute is populated by using the server name that hosts the mailbox when the mailbox is created.

The msExchHomeServerName attribute is not updated when a database is moved to a different server. Therefore, the Exchange Server 2007 CAS cannot determine the correct CAS for the availability request.

For more information about Availability Service logging, visit the following Microsoft website:For more information about the Get-ADUser cmdlet, visit the following TechNet website: For more information about the Import-Module ActiveDirectory command, visit the following TechNet website: