Any pre-rendering hook available?

[Jon Miller]

Am looking for a good approach to modifying how an email gets html
displayed. Specially work with other people using Outlook as their client and
when they put a smiley in their email, it comes across as the following:

<span style="font-family:Wingdings;color:#1F497D">J</span>

When I'm viewing the email, I just see these oddly placed "J" characters but
have since learned that they are supposed to be a smiley. Looking for
recommendations on how I'd accomplish this? devadvice around the html
rendering functions?

Thanks,
--
Jon Miller