Following the reusability principles, you can use https://github.com/PHPMailer/PHPMailer
<?php
require 'PHPMailerAutoload.php';
$mail = new PHPMailer;
$mail->isSMTP(); // Set mailer to use SMTP
$mail->Host="smtp1.example.com;smtp2.example.com"; // Specify main and backup server
$mail->SMTPAuth = true; // Enable SMTP authentication
$mail->Username="jswan"; // SMTP username
$mail->Password = 'secret'; // SMTP password
$mail->SMTPSecure="tls"; // Enable encryption, 'ssl' also accepted
$mail->From = '[email protected]';
$mail->FromName="Mailer";
$mail->addAddress('[email protected]', 'Josh Adams'); // Add a recipient
$mail->addAttachment('/var/tmp/file.tar.gz'); // Add attachments
$mail->addAttachment('/tmp/image.jpg', 'new.jpg'); // Optional name
$mail->Subject="Here is the subject";
$mail->Body = 'This is the HTML message body <b>in bold!</b>';
$mail->AltBody = 'This is the body in plain text for non-HTML mail clients';
if(!$mail->send()) {
echo 'Message could not be sent.';
echo 'Mailer Error: ' . $mail->ErrorInfo;
exit;
}
echo 'Message has been sent';
Source: How to attach two or multiple files and send mail in PHP