Creating EML File Using Griddler SendGrid Response

I am using Griddler for parsing incoming Sendgrid requests, now I want to create an EML file using the response that I am getting from the Sendgrid.

{
  text: 'hi',
  to: '"Mr Fugushima at Fugu, Inc" <hi@example.com>, Foo bar <foo@example.com>, Eichhörnchen <squirrel@example.com>, <no-name@example.com>',
  cc: 'cc@example.com',
  from: 'there@example.com',
  envelope: "{\"to\":[\"johny@example.com\"], \"from\": [\"there@example.com\"]}",
  charsets: { to: 'UTF-8', text: 'iso-8859-1' }.to_json,
  spam_score: '1.234',
  spam_report: 'Some spam report',
  headers: {...}
  attachment_info: {...}
}