PHP form processing, MIME types, email attachments for Entourage (for Mac)

I have created the below code which processes the attached HTML web form, and then sends the data to a recipient. I have tested it using Yahoo Mail, Gmail, Outlook Express (PC) and on Android, and the attachements show up as attachments.  

My problem is that the attachments involved, do not display correctly in the email program, Entourage for Macintosh. Instead, they show up as text inside the message, like this below:

"This is a multi-part message in MIME format.

--==frontier
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

The following person has applied online:

Name: tr
Phone: r
Email: tr
Address: t
Educational Level: r
Additional Info:
How they heard of us:


--==frontier
Content-Type: application/vnd.openxmlformats-officedocument.wordprocessingml.document;
name="testhey.docx"
Content-Disposition: attachment;
Content-Transfer-Encoding: base64

UEsDBBQABgAIAAAAIQDd/JU3ZgEAACAFAAATAAgCW0NvbnRlbnRfVHlwZXNdLnhtbCCiBAI ooAAC
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAC0
VMtuwjAQvFfqP0S+Vomhh6qqCBz6OLZIpR9g7A1Y9Uv28vr7bg JEVQtBKuUSKVnvzOzsxIPR2pps
CTFp70rWL3osAye90m5Wso/JS37PsoTCKWG8g5JtILHR8PpqMNkESBl1u1SyOWJ44DzJOViRC h/
..."

PHP process code is below, and the apply-now.html (web form) is attached.

Thanks in advance!

<?php


   $to="obsurf@seniorssharing.org";
   $subject="Online Application Received";
   $from = stripslashes($_POST['fullname'])."<".stripslashes($_POST['email']).">";

   // generate a random string to be used as the boundary marker
   //$mime_boundary="==Multipart_Boundary_x".md5(mt_rand())."x";
       $mime_boundary="==frontier";

   // now we'll build the message headers
   $headers = "From: $from\r\n" .
   "MIME-Version: 1.0\r\n" .
      "Content-Type: multipart/mixed;\r\n" .
      " boundary=\"{$mime_boundary}\"";


   $fullname= stripslashes( $_POST['fullname']);
   $phone= stripslashes( $_POST['phone']);
   $address= stripslashes( $_POST['address']);
   $email= stripslashes( $_POST['email']);
   $education= stripslashes( $_POST['education']);
   $additional= stripslashes( $_POST['additional']);
   $reference= stripslashes( $_POST['reference']);
 $message="The following person has applied online: \n\n ";
 $message.="Name: $fullname \n";
 $message.="Phone: $phone \n";
 $message.="Email: $email \n";
 $message.="Address: $address \n";
 $message.="Educational Level: $education \n";
 $message.="Additional Info: $additional \n";
 $message.="How they heard of us: $reference \n";




   $message = "This is a multi-part message in MIME format.\n\n" .
      "--{$mime_boundary}\n" .
      "Content-Type: text/plain; charset=\"iso-8859-1\"\n" .
      "Content-Transfer-Encoding: 7bit\n\n" .
   $message . "\n\n";

  
   foreach($_FILES as $userfile){
      // store the file information to variables for easier access
      $tmp_name = $userfile['tmp_name'];
      $type = $userfile['type'];
      $name = $userfile['name'];
      $size = $userfile['size'];

      
      if (file_exists($tmp_name)){

         if(is_uploaded_file($tmp_name)){
 	
      
            $file = fopen($tmp_name,'rb');
 	
            // read the file content into a variable
            $data = fread($file,filesize($tmp_name));

          
            fclose($file);
 	
           
            $data = chunk_split(base64_encode($data));
         }
 	
        
         $message .= "--{$mime_boundary}\n" .
            "Content-Type: {$type};\n" .
            " name=\"{$name}\"\n" .
            "Content-Disposition: attachment;\n" .
          //  " filename=\"{$fileatt_name}\"\n" .
            "Content-Transfer-Encoding: base64\n\n" .
         $data . "\n\n";
      }
   }
 
   $message.="--{$mime_boundary}--\n";
   // now we just send the message
   if (@mail($to, $subject, $message, $headers))
         echo '<meta http-equiv="Refresh" content="0; URL=thanks.html">';    
    else
         echo "Failed to send. Please contact us at: 510.658.7003";

?>

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apply-now.html