[EWS] [MailApp] Call Echange Web Service using SOAP and JavaScript

Hi,

I would like to know how to send SOAP message to EWS using JavaScript?

I have App for Office type Mail and I can send this SOAP message using this code:
Office.content.mailbox.makeEwsRequestAsync(envelope, callback);

but this function have limit 1MB for request/response:(.
http://msdn.microsoft.com/en-us/library/office/fp142267(v=office.15).aspx

I need to get/download selected email with all attachments.

Thanks for help!