Possible to send html-formatted email?

[RGould8 at aol.com]

I'm using the libSMTP v1.5.0 Email Client Example and I'm having trouble 
sending an HTML-formatted email message.  I've got the "save as plain text only" 
checkbox UNCHECKED, so that's not the problem.  I've been able to send 
plain-text emails just fine.

Can anyone tell me if I need special headers to get email clients to parse 
the data as formatted HTML?  I've experimented with both the AOL 9.0 client and 
the AppleMail client in Panther with no luck.