Iterate over emails in a .mbox file and output bouncing emails

iterate_bouncing_email_mbox.js

var Mbox = require('node-mbox');
var MailParser = require("mailparser").MailParser;

var mbox = new Mbox('inbox.mbox', { /* options */ });

var bouncingEmails = [];

mbox.on('message', function(msg) {
  var mailparser = new MailParser();
  mailparser.on("end", function(mail) {
    function _process() {
      if (mail.text) {
        var matches = mail.text.match(/([0-9a-z*](?:[-+*\.\w]*[0-9a-z]*)@(?:[0-9a-z][-\w]*\.)+[a-z]{2,9})/i);
        if (matches) {
          console.log(matches[0]);
          bouncingEmails.push(matches[0]);
        }
      }
    }

    if (mail.from[0].address === '[email protected]' && mail.subject.match(/Delivery Status Notification \(Failure\)/i)) {
      _process();
    } else if (mail.text) {
      var isMatching = [/550-5\.1\.1/i, /550 5\.1\.1/i, /550-5\.1\.0/i, /550 5\.1\.0/i, /550-5\.1\.10/i, /550 5\.1\.10/i, /5\.5\.0/i, /5\.3\.0/i].some(function(re) { return mail.text.match(re); });
      if (isMatching) { _process() }
    }
  });

  mailparser.write(msg);
  mailparser.end();
});

mbox.on('error', function(err) {
  console.log('got an error', err);
});

mbox.on('end', function() {});

Each bouncing email is output on a new line, you can then pipe the result to another command to further process it:

node index.js | xargs -I {} echo bouncing {}