By changing the FROM attribute to
email@example.com, the recipient cannot reply to the ACTUAL sender of the
form based web inquiry using the reply function of most email programs
and REPLYTO is supported in CF 5 and CFMX.
So the workaround is to use the cfmailparam tag to accomplish the task...
<cfmailparam name="Reply-To" value="""#Firstname# #Lastname#""