LaunchControl eases and helps improve the integrity of mail delivered via Mandrill templates.


Add this line to your application's Gemfile:

gem 'launch_control'

And then execute:

$ bundle

Or install it yourself as:

$ gem install launch_control

Within your application (for a Rails app, typically /config/initializers/launch_control.rb), setup your Mandrill API key you wish to use:

LaunchControl.configure do |config|
  config.mandrill_api_key = 'your_key_here'


To start using Launch Control, you first need to create a contract class:

class ThankyouEmail < LaunchControl::MandrillContract
  def template

  def validations
      first_name: 'string',
      last_name:  'string'

Here we define which Mandrill template id we are going to use, and which global merge variables we require to use this template safely. Validations use the Hash Validator gem, check it out for an idea of what's possible.

Now to send an email, we can use our MandrillContract subclass and simply push in all the details required as a hash:

mailer =
mailer.deliver(to: '[email protected]', subject: 'Bring it home safely', first_name: 'Pastor', last_name: 'Maldonado')
   => true

Now if you try and deliver this without the appropriate content, you'll be pulled up on it:

mailer.deliver(to: '[email protected]', subject: 'I know what I\'m doing', first_name: 'Kimi')
  => false

  => {:last_name=>"string required"}


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at[USERNAME]/launch_control.


The gem is available as open source under the terms of the MIT License.