Exchange Server doesn't display all OUs when it creates a new mailbox

Original KB number:   3038717

Symptoms

When you create a new mailbox together with a new user account in Exchange Server, the complete list of organizational units (OUs) isn't displayed as expected.

Cause

Exchange Control Panel (ECP) can display no more than 500 OUs. When there are more than 500 OUs, a new window is generated, and this window is either blank or contains a message (There are more items to show in this view).

Resolution

To resolve this issue, follow these steps:

1. Determine the number of OUs on the Exchange Server mailbox server. To do this, run the following command in a shell:

   (Get-OrganizationalUnit -ResultSize unlimited).count
   

2. On the Exchange Server mailbox server, go to the following folder:

   drive:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\ecp

3. Add the following lines in the web.config file just above </appsettings>:

   <!-- allows the OU picker when placing a new mailbox in its designated organizational unit to retrieve all OUs - default value is 500 -->
   <add key="GetListDefaultResultSize" value="500" />
   

   Note

   The value of GetListDefaultResultSize key should exceed the number of OUs that you found in step 1. Additionally, you will have to add this value every time that you install a cumulative update.

4. In IIS Manager, restart the MSExchangeECPAppPool application pool.

Caution

Any customized Exchange or Internet Information Server (IIS) settings that you made in Exchange XML application configuration files on the Exchange server (for example, web.config files or the EdgeTransport.exe.config file) will be overwritten when you install an Exchange Cumulative Update. For more information, see Upgrade Exchange to the latest Cumulative Update.