HTML-Mail => OE/OL works & NM doesn't

Hello PHP-Programmers, I am trying to send an HTML-Email... It works with Outlook and Outlook Express but it does not work with Netscape Messanger... Why?... These are the headers I am using... $boundary = "----=_MIME_" . uniqid("") . "_MIME_"; $boundary2 = "----=_MIME_" . uniqid("") . "_MIME_"; $mailprog = "/usr/sbin/sendmail -t"; $fd = popen( $mailprog, "w" ); fputs( $fd, "To: $email\n" ); fputs( $fd, "From: robot@xxx.de\n" ); fputs( $fd, "Subject: xxx.de Express Service!\n" ); fputs( $fd, "MIME-Version: 1.0\n" ); fputs( $fd, "Content-type: multipart/related;\n"); fputs( $fd, " boundary=\"$boundary\";\n"); fputs( $fd, " type=\"multipart/alternative\"\n"); fputs( $fd, "X-Priority: 3\n"); fputs( $fd, "X-Mailer: xxx.de Express!\n"); fputs( $fd, "Content-Transfer-Encoding: 8bit\n"); fputs( $fd, "Date: " . date("D, d M Y H:i:s",time()) . " +0100\n"); fputs( $fd, "Status: RO\n"); fputs( $fd, "\nThis is a multi-part message in MIME format.\n\n"); fputs( $fd, "--$boundary\n"); fputs( $fd, "Content-Type: multipart/alternative;\n"); fputs( $fd, " boundary=\"$boundary2\"\n\n\n"); fputs( $fd, "--$boundary2\n"); fputs( $fd, "Content-Type: text/html\n"); fputs( $fd, "Content-Transfer-Encoding: quoted-printable\n"); fputs( $fd, " boundary=\"$boundary2\"\n\n\n"); fputs( $fd, "$html_code"); fputs( $fd, "--$boundary2\n"); pclose( $fd ); Thanks Joseph