PDF conversions are supported! From the Preferences dialog, please choose the "Convert to PDF" option from either the "E-mail Client" or "Address book Client" dropdown menus.
Please note: While some attachments like images will render in the converted PDF, not all attachments will be displayed (This is similar to the behavior you see in an email -- some attachments require you to double-click). However, a complete listing of attachments will be still displayed at the top of the PDF.