This script will try adding multiple email addresses to a recipient list using the NL API.

nlapiadd.rb

require 'httparty' 
require 'JSON'

url = 'https://sendgrid.com/api/newsletter/lists/email/add.json'

#the arrays containg email addreses and custom tags
emails = ['andrei@sendgridson2.com','andrejstg@gmai2l.com']
names = ['Andrei1','Andrei2']
array = []

#go through the emails array.
emails.each_with_index do |a,idx|
  #created a hash that stores the email and name parameters of the larger 'data' param
	hash = {
		 	:email => a,
		    :name => names[idx]
			}
			#convert the hash to json and concatenate it with the 'data' param
	array << hash.to_json

end

puts array

response = HTTParty.post url, :body => {
	:api_user => 'username',
	:api_key => 'password',
	:list => 'TestSGlist',
	:data => array

}

puts response.request.options
puts response.body