Digital Signature Button Missing

When using Outlook rich text instead of MS Word as a e-
mail editor, you can add Encrypt and Digital Signature
Button to your tool bar. However, when using MSWord as
your e-mail editor, there is no such buttons to add to
MSWord's tool bar. How can I add both buttons to the
tool bar when using MSWord as an e-mail editor?

I do wish to occasionally digitally sign messages or
encrypt but don't want it activated for ALL messages.
That is why I like the buttons. Currently I am having to
switch between MS Word and Outlook rich text to
accomplish this task. I like using Word as an e-mail
editor, so I would like to add the same buttons to word's
e-mail template.

Thanks