This program reads a folder or file, and tests, and screen prints only Emails. It is built for large amounts of data.

pool.js

var fs = require('fs')
var events = require('events')
var util = require('util')
var path = require('path')
 
var FsPool = function (dir) {
	events.EventEmitter.call(this)
	this.dir = dir;
	this.files = [];
	this.active = [];
	this.threads = 1;
	this.on('run', this.runQuta.bind(this) );
};
// So will act like an event emitter
util.inherits(FsPool, events.EventEmitter);
 
FsPool.prototype.runQuta = function() {
	if(this.files.length === 0 && this.active.length === 0) {
		return this.emit('done');
	}
	if(this.active.length < this.threads) {
		var name = this.files.shift()
	
		this.active.push(name)
		var fileName = path.join(this.dir, name);
		var self = this;
		fs.stat(fileName, function (err, stats) {
			if(err)
				throw err;
			if( stats.isFile() ) {
				fs.readFile(fileName, function(err, data) {
					if(err)
						throw err;
					self.active.splice(self.active.indexOf(name), 1)
					self.emit('file', name, data);
					self.emit('run');
				});
			} else {
				self.active.splice(self.active.indexOf(name), 1)
				self.emit('dir', name);
				self.emit('run');
			}
		});
	}
	return this
};

FsPool.prototype.init = function() {
	var dir = this.dir;
	var self = this;
	fs.readdir(dir, function(err, files) {
		if(err)
			throw err;
		self.files = files
		self.emit('run');
	});
	return this
};

module.exports = FsPool;

readOnly

#!/usr/bin/env node 

GLOBAL.os		= require('os');
GLOBAL.fs		= require('fs');
GLOBAL.sys		= require('sys');
GLOBAL.util		= require('util');
GLOBAL.path		= require('path');
GLOBAL.pool		= require('./pool.js');
GLOBAL.program	= require('commander');
GLOBAL._		= require('underscore');
GLOBAL.reader   = require('line-reader');
GLOBAL.childp	= require('child_process');
GLOBAL.tmp		= os.tmpDir();

_.str = require('underscore.string');
_.mixin(_.str.exports());

function parceList ( val ){
	var all = []
	var list = val.split(',');
	for (var i = list.length - 1; i >= 0; i--) {
		all.push( new RegExp(  list[i] ) );
	return  all;
}

program
	.option('-i, --in <path>', 'Path with in' )
	.option('-r, --recursive', 'Recursive')
	.option('-e, --encoding <encoding>', 'encoding')
	.option('-t, --test <test1,test2...>', 'Test in RegExp', parceList);

program.parse(process.argv);

//Carpeta o archivo a leer
const inner = path.resolve( program.in ? program.in : './data.txt' );

// Expresiones regulares a testear
const exp = program.test || [
	/[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}/gm,
	/[a-zA-Z0-9._-]+&#64[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}/gm,
	///^[Form]/
];

if( program.recursive ){

	var fsPool = new pool(inner);
	fsPool.on('file', function (fileName, fileData) {
		console.log('file name: ' + fileName);
		var datas = fileData.toString('utf8');
		var test = [];
		exp.forEach( function (reg ){
			test = _.union( test, datas.match(reg) || [] );
		});

		if( _.isArray(test) && test.length > 1 ){
			for (var i = test.length - 1; i >= 0; i--)
				console.log( test[i] );
		}
	});
	fsPool.on('dir', function (dirName) {
		console.log('dir name: ' + dirName);
	})
	fsPool.on('done', function() {
		console.log('done Ok');
	});
	fsPool.init();
// Ejecusion Clasico
} else {

	console.log('file name: ' + inner);
	reader.eachLine(inner, function (line, last) {
		var test = [];
		
		exp.forEach( function (reg ){
			test = _.union( test, datas.match(reg) || [] );
		});

		if( _.isArray(test) && test.length > 1 ){
			for (var i = test.length - 1; i >= 0; i--)
				console.log( test[i] );
		}
		if(last && data.length > 1){
			console.log('done Ok');
			process.exit();
		}
	});
}
}