I had written about the lack of option in 2010 RC & RTM to change the OWA theme by an end user in one of my article. Guess what? Themes can be changed by an end user from an Outlook Web App (OWA) session running on 2010 SP1 Beta. There are 31 themes in the Beta version.
After logging into the OWA, click on “Options” on the top right hand side, which brings the theme selection option.
Notice that many parts of the OWA page changes as you switch to a new theme.
You can block the users from changing the themes either by configuring “OWA Mailbox Policies” or by disabling it on the properties of OWA virtual directory. In order to disable the feature in the OWA virtual directory, navigate to Recipient Configuration -> Client Access -> OWA -> Properties. Click on “Segmentation” tab, highlight “Theme Selection” and click Disable.
Once the themes are blocked, users don’t get the theme selection option in OWA.