Good morning,
I'm trying to implement GPP for IE settings from Server 2012 for both IE 9 and IE 10 so that I can upgrade my last couple 2k8R2 servers to 2012 and move away from using IE Maintenance. (Windows 7 32bit clients running Office 2010 and IE 9) To create this GPO I made a copy of my existing laptop GPO, which used IE Maintenance and then added profiles for IE 8&9 and IE 10 under GPP. I also reset the Internet Explorer Maintenance settings so they are blank.
The GPOs are applying and all settings are applying correctly, I've only configured Favorites, Homepage and Proxy Settings. The problem is that once these settings apply, users can no longer access shared mailboxes in Outlook. Their normal email accounts work fine, but the shared mailboxes won't update if they're already in Outlook, and won't add if they try to re-add them, I receive a message about Microsoft Exchange not being available even though their normal account is connected successfully.
I can replicate this behavior on any machine and with any user by dropping them in the test OU to get this new GPO, and as soon as I put them back in an OU with the old GPO and gpupdate their shared email boxes work perfectly.
My guess is this has something to do with the way the proxy settings are handled with the GPP that is different from IE Maintenance, but all the settings that are configurable from the GPOs are identical.