A working PHP script that adds multiple addresses for the ME API.

NLAPI2.php

<?php
	$username='SG_username';
	$password='SG_password';
	
	$url = 'https://sendgrid.com/api/newsletter/lists/email/add.json?api_user='.$username.'&api_key='.$password; 
	// API call including username and password
	
	$email=array('email@domain.com','mail@example.com','mailz@email.com'); 
	//initialize the email array
	$name=array('Name1','Name2','Name3'); 
	//initialize the name array
	
	$listname='name_of_recipient_list';
	
	$str= '&list=' . $listname; 
	//concatenate the original URL with the listname
 
	for ($i=0;$i<count($email);$i++) {
		$str.= '&data[]={"email":"'.$email[$i] . '","name":"'.$name[$i].'"}';
	}
	echo $url.$str;
	$api=file_get_contents($url . $str); 
	// run the API call
	echo $api;
 ?>