const OpenDKIM = require('node-opendkim');

try {
  var opendkim = new OpenDKIM();
  opendkim.verify({
    id: undefined // optional (default: undefined)
  });

  // Adding one header at a time, when finished call opendkim.eoh()
  var header = 'From: <[email protected]>';
  opendkim.header({
      header: header,
      length: header.length
  });
  opendkim.eoh();

  // Adding body chunks, when finished call opendkim.eom().  This too
  // can take many chunks.  Do NOT include the terminating DOT.
 var body = 'this is a test';
  opendkim.body({
      body: body,
      length: body.length
  });
  // This does the final validation, and will throw an error if there is one.
  opendkim.eom();
} catch (err) {
  console.log(err);
}