Contact form file send

contact_me.php

<?php
if($_POST)
{
    $to_email       = "a.kazakov@computer-ufa.ru"; //Recipient email, Replace with own email here
    $from_email     = "noreply@YOUR-DOMAIN.com"; //From email address (eg: no-reply@YOUR-DOMAIN.com)
    $subject        = "subject";
    
    //Sanitize input data using PHP filter_var().
    $phone1      = filter_var($_POST["phone1"], FILTER_SANITIZE_STRING);
    $phone2      = filter_var($_POST["phone2"], FILTER_SANITIZE_STRING);
    $phone3      = filter_var($_POST["phone3"], FILTER_SANITIZE_STRING);
       
    //email body
    $message_body = $phone1.$phone2.$phone3 ;

    ### Attachment Preparation ###
    $file_attached = false;
    if(isset($_FILES['file'])) //check uploaded file
    {
        //get file details we need
        $file_tmp_name    = $_FILES['file']['tmp_name'];
        $file_name        = $_FILES['file']['name'];
        $file_size        = $_FILES['file']['size'];
        $file_type        = $_FILES['file']['type'];
        $file_error       = $_FILES['file']['error'];

        //exit script and output error if we encounter any
        if($file_error>0)
        {
            $mymsg = array( 
            1=>"The uploaded file exceeds the upload_max_filesize directive in php.ini", 
            2=>"The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form", 
            3=>"The uploaded file was only partially uploaded", 
            4=>"No file was uploaded", 
            6=>"Missing a temporary folder" ); 
            
            $output = json_encode(array('type'=>'error', 'text' => $mymsg[$file_error]));
            die($output); 
        }
        
        //read from the uploaded file & base64_encode content for the mail
        $handle = fopen($file_tmp_name, "r");
        $content = fread($handle, $file_size);
        fclose($handle);
        $encoded_content = chunk_split(base64_encode($content));
        //now we know we have the file for attachment, set $file_attached to true
        $file_attached = true;

    }
    
    if($file_attached) //continue if we have the file
    {
        $boundary = md5("sanwebe"); 
        //header
        $headers = "MIME-Version: 1.0\r\n"; 
        $headers .= "From:".$from_email."\r\n"; 
        $headers .= "Content-Type: multipart/mixed; boundary = $boundary\r\n\r\n"; 
        
        //plain text 
        $body = "--$boundary\r\n";
        $body .= "Content-Type: text/plain; charset=ISO-8859-1\r\n";
        $body .= "Content-Transfer-Encoding: base64\r\n\r\n"; 
        $body .= chunk_split(base64_encode($message_body)); 
        
        //attachment
        $body .= "--$boundary\r\n";
        $body .="Content-Type: $file_type; name=\"$file_name\"\r\n";
        $body .="Content-Disposition: attachment; filename=\"$file_name\"\r\n";
        $body .="Content-Transfer-Encoding: base64\r\n";
        $body .="X-Attachment-Id: ".rand(1000,99999)."\r\n\r\n"; 
        $body .= $encoded_content; 
    }else{
        //proceed with PHP email.
        $headers = "From:".$from_email."\r\n".
        'X-Mailer: PHP/' . phpversion();
        $body = $message_body;
    }

    $send_mail = mail($to_email, $subject, $body, $headers);
   
    header('Location: http://dev.ak-agency.ru/marlena/');
}

index.html

<form id="file-form" method="post" action="contact_me.php" enctype="multipart/form-data">
	<input type="hidden" name="MAX_FILE_SIZE" value="20971520" />            	
  <label class="form-label">Загрузите фото:</label>
  <div class="w-input form-input file">
  	<input type="file" name="file">
  </div>
  <label class="form-label">Ваш телефон:</label>
  <input type="text" placeholder="+7" name="phone1" class="w-input form-phone-input">
  <input type="text" placeholder="123" name="phone2" class="w-input form-phone-input _2">
  <input type="text" placeholder="1234567" name="phone3" class="w-input form-phone-input _3">
  <div class="form-btn-wrap">
    <input type="submit" value="Оставить заявку" class="w-button form-btn">
  </div>
</form>