title: Unable to send email via gmail api to multiple senders
body: <p>We're using the new gmail api on iOS to send emails and everything works great for messages with single recipients.  When we specify more than one in the "to" field, we get the following error:</p>
  
  <pre><code>Error Domain=com.google.GTLJSONRPCErrorDomain Code=400 "The operation couldn’t be completed. (Invalid to header)
  </code></pre>
  
  <p>I have verified the content we are sending is in fact a valid rfc822 message.</p>