HowTo – Exchange Server – No OrganizationalUnit will be displayed by creating new Mailbox User

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Today I wanted to create a new Mailbox User over the ECP and the OU list was empty. So I was shocked and a little panic was noticed.

So what has changed?

Rights? No!

OUs? Yes, there was some OU’s added last weeks.

So I find the following KB at Microsoft:

What, Exchange has a default list of 500 for OU’s? Ok, lets change this, because we are now over 500 🙂

  • First connect to one of the Exchange Server
  • Start Exchange Powershell and get a count of your OU’s

Powershell Command for Count OU’s

(Get OrganizationalUnit-ResultSize unlimited) .count  

  • Search for the following directory


%systemdrive%:Program Files\Microsoft\Exchange Server\V15\ClientAccess\ecp

  • Edit web.config in </appsettings>

Code to add

<!-- 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" />

  • Last step is to Restart an IIS App Pool called

IIS App Pool


Note: The value GetListDefaultResultSize  should be greater than the Count of the Powershell Command before and the value must be added every time you install a cummulative update on your Exchange Servers.


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