Add an attachment to confirmation emails in Paid Memberships Pro

my_pmpro_email_attachments.php

/*
	Add an attachment to confirmation emails.
	
	Requires PMPro v1.7.14+
*/
function my_pmpro_email_attachments($attachments, $email)
{
	//make sure it's a checkout email (but not the admin one)
	if(strpos($email->template, "checkout_") !== false && strpos($email->template, "admin") === false)
	{
		//make sure attachments is an array
		if(is_array($attachments))
			$attachments = array();
			
		//add our attachment
		$attachments[] = ABSPATH . "/wp-content/uploads/2014/09/Picture1.jpg";
	}
	
	return $attachments;
}
add_filter('pmpro_email_attachments', 'my_pmpro_email_attachments', 10, 2);