I just had a horrible thought:
For months now I've been using the new MS fonts in my emails - the body text is in Calibri (the default for Outlook 2007), and I use of smattering of Consolas in my signature to space out phone numbers and other contact details neatly. I think it looks pretty good, very modern, very clean.
BUT - what if the recipients don't have these fonts installed on their system? How does it degrade? Will they see a sensible alternative, such as Arial or Verdana, or will it just render in *shudder* Times New Roman!? People will think I have no taste! That would be nearly as bad as those folk who insist on sending business emails in 16-point fuschia Comic Sans MS!