Exchange 2013 EAC Not Showing All OU's in Active Directory

I came across another issue with Exchange 2013 EAC, in that it wouldn't list the entire Active Directory Organizational Unit structure when adding mailboxes and contacts.
The problem is: EAC only shows 500 items by default, which is pretty stupid considering there are a lot of environments with well over 500 objects.

The fix is to edit the web.config file to adjust the max result size.

On each 2013 Mailbox or Multi-role Server, browse to:

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

Or if you have separated the roles, on each CAS machine, browse to:

C:\Program Files\Microsoft\Exchange Server\V15\FrontEnd\HttpProxy\ecp

Open web.config in notepad, and scroll down to the "appsettings" section

Right above:

< /appsettings >

add the following:

< !--allows the OU picker during placing a new mailbox in its designated Organizational Unit to retrieve all OUs - default value is 500 -->
< add key="GetListDefaultResultSize" value="1000" />

**Note** You can add the key anywhere in appsettings, but I add it at the bottom so it's easily found.

Close and save the web.config file, then close and re-open the EAC and it will now display 1000 results...as it should've in the first place.