Unable to make use of Postbin

[eegrok]

I'm trying to debug an issue with the client, and I've got some code I'm using -- pulled straight from the github page, substituting in my api key and domain / email addresses. When I run it having it send the email using the regular mailgun client, it works fine. If I use the extra parameters, specifying bin.mailgun.net and the code -- it gives me the following error:

405 Method Not Allowed

any tips on how to make this work?

(I am of course substituing my actual api key and domain in the code -- I've tried both my live domain and sandbox, but they both give the 405)

$api_key = 'my-api-key'
$domain = 'my-domain'

def test_postbin(mg_client, subject)
  mg_client ||= Mailgun::Client.new($api_key, "bin.mailgun.net", "7d9a62e", ssl = false)
  message_params = {  from: "me@#{$domain}",
    to: 'testuser@myotherdomain.com',
    subject: subject,
    text: 'It is really easy to send a message -- hopefully this works!'
  }
  mg_client.send_message($domain, message_params)
end

mg_client = Mailgun::Client.new($api_key)
test_postbin(mg_client, "testing with mailgun")
test_postbin(nil, "testing with postbin")