asynceachparallel.js

var async = require('async');
var emails = ["[email protected]","[email protected]"];

async.each(emails,function(singleEmail,callback) {
  async.waterfall([
    function(callback) {
      // code to send email.
      callback(null,Flag);
    },
    function(emailSentOrNot,callback) {
      // Update DB.
    }
  ],function(err,data) {
  });
},function(err,data) {
  // Once all done, comes here.
});