headers help

Hello all, I must confess I know the very basics on this language and have even less knowledge about http headers. I wish you could help me out on this: I have a form that sends html e-mails and an optional file as attachment. The issue is that, if the file is NOT send, the e-mail receives two times the same content, one that gets read by the mail clients as HTML properly, and, a literal print of my $message string variable that contains: <html> <head> </head> <boby> <table>My form contents</table> </body> </html> I believe that the reason for this lies on the $header options, probably on line number 8 ? Here is the, what I believe, is the relevant code: http://pastebin.com/5ywdK0UU What should I do, to avoid this extra <html> code on the e-mail messages ? Thanks in advance, Márcio