index.php
<?php
function MailWithAttachment($to, $subject, $message, $senderMail, $senderName, $files){
    $from = $senderName." <".$senderMail.">"; 
    $headers = "From: $from";
    // boundary 
    $semi_rand = md5(time()); 
    $mime_boundary = "==Multipart_Boundary_x{$semi_rand}x"; 
    // headers for attachment 
    $headers .= "\nMIME-Version: 1.0\n" . "Content-Type: multipart/mixed;\n" . " boundary=\"{$mime_boundary}\""; 
    // multipart boundary 
    $message = "--{$mime_boundary}\n" . "Content-Type: text/html; charset=\"UTF-8\"\n" .
    "Content-Transfer-Encoding: 7bit\n\n" . $message . "\n\n"; 
    // preparing attachments
    if(count($files) > 0){
        for($i=0;$i<count($files);$i++){
            if(is_file($files[$i])){
                $message .= "--{$mime_boundary}\n";
                $fp =    @fopen($files[$i],"rb");
                $data =  @fread($fp,filesize($files[$i]));
                @fclose($fp);
                $data = chunk_split(base64_encode($data));
                $message .= "Content-Type: application/octet-stream; name=\"".basename($files[$i])."\"\n" . 
                "Content-Description: ".basename($files[$i])."\n" .
                "Content-Disposition: attachment;\n" . " filename=\"".basename($files[$i])."\"; size=".filesize($files[$i]).";\n" . 
                "Content-Transfer-Encoding: base64\n\n" . $data . "\n\n";
            }
        }
    }
    $message .= "--{$mime_boundary}--";
    $returnpath = "-f" . $senderMail;
    //send email
    $mail = @mail($to, $subject, $message, $headers, $returnpath); 
    //function return true, if email sent, otherwise return fasle
    if($mail){ return TRUE; } else { return FALSE; }
}
if(!empty($_POST['data'])){
    //email variables
    $to = '[email protected]';
    $from = '[email protected]';
    $from_name = 'PDF FIle';
    //attachment files path array
    $file = base64_decode($_POST['data']);
    $subject = 'PHP Email with attachment'; 
    $html_content = '<h1>PHP Email with attachment</h1>';
    //call MailWithAttachment() function and pass the required arguments
    $send_email = MailWithAttachment($to,$subject,$html_content,$from,$from_name,$file);
    //print message after email sent
    echo $send_email?"<h1> Mail Sent</h1>":"<h1> Mail not SEND</h1>";
} else {
    echo "No Data Found";
}
?>