MailsViewer is a mails preview Engine which provides a table view for all mails under tmp/mails. So you can easily preview the mails in non-production mode and no longer need to worry about accidentally sending a test email to someone else’s address.

MailsViewer is a fork of tomlion's original code and I'm glad to be the maintainer; thanks go to him for getting this thing started!


  • MailsViewer should be used with Rails >= 3.1

  • In your config file, You should require "sprockets/railtie"if you don't require 'rails/all' and enable assets pipeline by adding config.assets.enabled = true to config file


Add the gem to your Gemfile :

gem "mails_viewer"

Set ActionMailer's delivery method to :file :

config.action_mailer.delivery_method = :file

put this in your routes.rb:

mount MailsViewer::Engine => '/delivered_mails'

Now just load up http://localhost:3000/delivered_mails


You can choose to send out some mails to the inbox instead of just storing them in the file system by specifying which mails to sent:

  • : send_if - Send mails that satisfy some condition
config.action_mailer.delivery_method = :file
config.action_mailer.file_settings = {
  location: 'tmp/mails',
  smtp_settings: {
    address:              "localhost",
    port:                 25,
    domain:               'localhost.localdomain',
    user_name:            nil,
    password:             nil,
    authentication:       nil,
    enable_starttls_auto: true
  send_if: lambda { |mail| { |address| ["[email protected]"].include?(address) }.any? }

Now any mails sent to [email protected] will not only store in the filesystem for you to browse later, but also send out to his inbox.



MailsViewer is maintained by (Originally

Special thanks to tomlion for starting the project.

Copyright (c) 2012 Dingding Ye, ([email protected],