- 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
- On the Exchange Server 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>:
<!-- 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" />
- In IIS Manager, restart the MSExchangeECPAppPool application pool.