Why can't I use HTML code in my signature anymore?
The Microsoft Office Word 2007-based e-mail editor is the only e-mail editor provided in Microsoft Office Outlook 2007. This e-mail editor does not support HTML code in signatures.
Note You cannot disable the default e-mail editor in Outlook 2007; other e-mail editors are no longer supported.
For security and performance reasons, some functionality from earlier versions of the e-mail editor is no longer available, including animated .gifs, embedded flash objects, and some advanced HTML and CSS formatting. You can use your Web browser to search the Web to find information about alternative ways to reproduce some of this functionality.