sendmail -t won't work

I have a big problem having sendmail to work through PHP scripts. We have a RedHat6.2 Linux server with Apache 1.3.12 and PHP4 installed. This is script: $sendmail = "/usr/lib/sendmail"; $fp = popen( "$sendmail -t", "w"); fwrite($fp, "To: $firstname $lastname <$useremail>\n"); fwrite($fp, "From: Lars FORNELL <lars.fornell@limelab.com>\n"); fwrite($fp, "Subject: Test\n"); fwrite($fp, "Organization: Test\n\n\n"); fwrite($fp, "$subject\n"); pclose($fp); This is what the maillog looks like: Jun 8 06:07:03 linux845 sendmail[24641]: GAA24641: to=Lars FORNELL <lars.fornell@limelab.com>, delay=00:00:00, mailer=local, stat=User unknown But no mails get send, maybe because of the "stat=User unknown" in the log, but how can I avoid that? Thanks in advance; Lars