7
It would be placed in the section that prints out the other headers, e.g.:
print MAIL "From: $recips";
print MAIL "To: $recips";
[color=ff0000]print MAIL "Content-Type: text/html; charset=ISO-8859-1";[/color]
print MAIL "Subject: $subjectnnn";
As I indicated, you may need additional headers too.
Sorry, but I don't have time to produce a complete, tested, working script here. If you don't get any additional help here, an option would be to contract someone (such as myself) to do the work.