In a Microsoft Exchange Server 2007 Client Access Server (CAS) proxy environment, you enable S/MIME in Microsoft Office Outlook Web Access (OWA) client-side. After you do this, OWA no longer highlights misspelled words. However, if you know that a word is misspelled and you right-click it, OWA still suggests a correct spelling for that word.
This issue occurs because the LocalHostName property was used to reference a background image for the misspelled words. When you have S/MIME enabled in an Exchange Server 2007 CAS proxy environment, OWA tries to download the background image from the back-end CAS server. However, this is not allowed.
To resolve this problem, install the following update rollup:
972076 Description of Update Rollup 2 for Exchange Server 2007 Service Pack 2
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about proxying, visit the following microsoft Web site: