OWA 2013 goes public

Public or Shared Computer?
That used to be the “Big Question” when logging on to OWA having Form-Based Authentication enabled (=default setting in Exchange 2007/2010/2013 and had to be manually enabled in Exchange 2003).

OWA2013Now with Outlook Web App 2013, the option to choose public or private computer is not enabled by default, but we can enable it in Exchange Management Shell (EMS).

Set-OwaVirtualDirectory -id "EX2013\owa (Default Web Site)" -LogonPagePublicPrivateSelectionEnabled $True


What I find interesting is that private computer is selected and that is a setting I want users to have to choose, as they had to in earlier versions of Exchange.

The difference between the two options is how long the session can be inactive before the user needs to log on again.

  • public or shared computer – 15 minutes
  • private computer – 24 hours

There is no way to configure the setting to be unchecked by default in Exchange Admin Center (EAC) or Exchange Management Shell (EMS), instead we need to modify logon.aspx that is found in *\V15\FrontEnd\HttpProxy\owa\auth
Note: Take a backup copy of the logon.aspx before you make any modifications to this file.

  1. Open *\V15\FrontEnd\HttpProxy\owa\auth\logon.aspx with your favorite editor
  2. GoTo line 214
  3. delete the word checked

<input id="chkPrvt" onclick="clkSec()" name="trusted" value="4" type="checkbox" checked role="checkbox" aria-labelledby="privateLabel"/>

<input id="chkPrvt" onclick="clkSec()" name="trusted" value="4" type="checkbox" role="checkbox" aria-labelledby="privateLabel"/>


Thanks to davidmmm, who posted Lee Derbyshir’s blog post How To Remove The Public Or Private Radio Button In Microsoft Outlook Web App 2010 in the Exchange Forum

To the question “Is this supported?”, I can only answer “I don’t know“.


  1. Great stuff!

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