docs: function sendMail(options) {
  
  	var i = 0
  	var cmds = [
  		'HELO ' + options.host,
  
  		// auth
  		'auth login',
  		new Buffer(options.username).toString('base64'),
  		new Buffer(options.password).toString('base64'),
  
  		// from to
  		'mail from:' + options.username,
  		CMD_RCPT_TO + options.to,
  
  		// message
  		'data',
  		CMD_MESSAGE,
  
  		'quit'
  	]
  	var message = [
  		'from:' + options.from,
  		'to:' + options.to,
  		'subject:' + options.subject,
  		'',
  		options.body,
  		'.'
  	]
  
  	prepairRcpt(cmds)
  
  	var client = net.connect({
  		host: options.host,
  		port: options.port
  	})
  
  	client.on('connect', function () {
  		console.log('connected')
  	})
  
  	client.on('data', function (data) {
  		console.log('Serer: ' + data.toString().replace(END_LINE, ''))
  
  		if (i >= cmds.length) {
  			client.end()
  			return
  		}
  
  		var cmd = cmds[i++]
  
  		if (cmd === CMD_MESSAGE) {
  			console.log('message body:')
  			message.forEach(function (line) {
  				console.log('> ' + line)
  				client.write(line + END_LINE)
  			})
  		} else {
  			console.log('ME: ' + cmd)
  			client.write(cmd + END_LINE)
  		}
  	})
  
  	client.on('error', function (er) {
  		console.log('error: ' + er)
  	})
  
  	client.on('end', function () {
  		console.log('send mail finish')
  	})
  }