- Determine the number of OUs on the Exchange Server 2013 mailbox server. To do this, run the following command in a shell: (Get-OrganizationalUnit –ResultSize unlimited).count
- On the Exchange Server 2013 mailbox server, go to the following folder:
<Drive>:\Program Files\Microsoft\Exchange Server\V15\ClientAccess\ecp
- Add the following lines in the web.config file just above </appsettings>:Note The value of GetListDefaultResultSizekey 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.
<!-- 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" />
- Restart MSExchangeECPAppPool.