电子邮件脚本格式不正确

我有这个脚本，它每月通过 cron 作业运行一次，向客户端发送 awstats 报告。由于对出站邮件服务器的限制越来越严格，我们最近不得不对其进行修改。遗憾的是，某些收件人在邮件正文中以原始 html 代码的形式收到报告。谁能从剧本中看出我哪里做错了？

    ########################## 
## Call to get awstats 
########################## 
$curl = curl_init(); 
curl_setopt($curl, CURLOPT_URL,"http://www.$your_domain:2082/awstats.pl" 
        ."?month=$report_month&year=$report_year&output=main&config=$your_domain" 
        ."&lang=en&framename=mainright"); 
curl_setopt($curl, CURLOPT_USERPWD, "$user:$password"); 
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1); 
//$attachment = curl_exec($curl); 
$attachment = "<br /><br /><div align='"center'"><a href='"$logo_link'"><img src='"$logo_path'" border='"0'" /></a>'n"; 
$attachment .= "<br /><font color='"#FF0000'"><b>AwStats Report for $your_domain ($report_monthname $report_year)</b></font></div>'n";
$attachment .= "<base href='"$awstats_img_path'">'n"; 
$attachment .= curl_exec($curl); 
curl_close($curl); 
########################## 
## Call to send email 
########################## 
$subject = "AwStats Report for $your_domain ($report_monthname $report_year)";
$header    = "From: " . $email_from . " <" . $email_from . ">'n";
$header .= "Reply-To: " . $email_from . "'n";
$header .= "MIME-Version: 1.0'n";
$header .= "Content-Type: multipart/mixed; boundary='"" . $uid . "'"'n'n";
$uid = md5(uniqid(time()));
$message = "--" . $uid . "'n";
$message .= "Content-type:text/html; charset=iso-8859-1'n";
$message .= "Content-Transfer-Encoding: 7bit'n'n";
$message .= $attachment . "'n'n";
mail($email_to, $subject, $message, $header);

我显然在这里省略了变量声明。但它们都在代码中。我实际上收到了邮件的抄送，它在桌面上的苹果邮件中显示正常。

谢谢长江