The RecipientResolutionTimeoutInSeconds property is available to modify the time limit of a cross-forest AutoDiscover operation in Exchange 2007

This article describes a property that you can use to increase the default time-out value for the Cross-Forest Availability service in Microsoft Exchange Server 2007.

The Cross-Forest Availability service has a time limit when the service performs an AutoDiscover operation for cross-forest users in the Active Directory directory service. By default, this time-out value is 10 seconds. If the AutoDiscover request does not finish in 10 seconds, the whole Availability Service request for the cross-forest user may time out.

Note An AutoDiscover request may not finish in the time-out period if one or more of the following conditions are true:

• The URL for the user is not cached.
• The AutoDiscover service is running slowly.
• The AutoDiscover service experiences network latencies.

You can use the RecipientResolutionTimeoutInSeconds property to control the time-out value. This RecipientResolutionTimeoutInSeconds property is set in the ASP.NET Web.config file. By default, this property has a value of 10 seconds. To modify the time-out value for the Cross-Forest Availability service, set the value for this property to between 20 seconds and 24 seconds. To do this, follow these steps:

1. Locate the Web.config file in the following directory:
   drive:\Program Files\Microsoft\Exchange Server\ClientAccess\exchweb\ews
2. Back up the existing Web.config file, and then rename the Web.config file to Web.config.bak1.
3. Open the Web.config file in Notepad.
4. Add the following section directly under the <Configuration> node.

   <appSettings>
        <add key=”RecipientResolutionTimeoutInSeconds” value=”24”/>
   </appSettings>

   Important This entry is case-sensitive. Input the entry exactly as shown. Also, if you add this section under any other node of the Web.config file, the section will not work.
    
5. Save the Web.config file.
6. Locate the Web.config file in the following directory:
   drive:\Program Files\Microsoft\Exchange Server\ClientAccess\Owa
7. Back up the existing Web.config file, and then rename the Web.config file to Web.config.bak1.
8. Open the Web.config file in Notepad.
9. Add the following section directly under the <Configuration> node.

   <appSettings>
        <add key=”RecipientResolutionTimeoutInSeconds” value=”24”/>
   </appSettings>
   
   

   Important This entry is case-sensitive. Input the entry exactly as shown. Also, if you add this section under any other node of the Web.config file, the section will not work. 
10. Save the Web.config file.

Note We recommend that you do not set this property to a value of more than 25 seconds.