TMG OWA logoff

On any TMG publishing rules, on the Application Settings tab, modify the "Published server logoff URL" to be "owa/auth/signout.aspx".

Then, on any CAS servers, navigate to and open

%ExchangeInstallPath%\Frontend\HttpProxy\OWA\web.config

and delete this line:

<add key="LogonSettings.SignOutKind" value="LegacyLogOff" />

Thirdly, on any mailbox servers, navigate to these files

%ExchangeInstallPath%\ClientAccess\OWA\web.config

%ExchangeInstallPath%\ClientAccess\ECP\web.config

and delete the same line from both files.

Lastly, do an IISreset on each affected server.

Источник: https://social.technet.microsoft.com/Forums/ie/en-US/123e8a50-5525-4ce4-9b7a-9c289bb3c0b9/owa-2013-publish-through-tmg-2010-logoff-url-problem?forum=Forefrontedgegeneral