PostmarkMailer

This gem is designed to provide a (nearly) drop-in replacement for Ruby on Rails' ActionMailer for those wishing to deliver emails using Postmark's Templates API. Its interface mimics that of ActionMailer so switching existing mailers should require minimal effort, and usage should be familiar to most Ruby on Rails developers.

NOTE: This gem only provides a means of delivering transactional emails from a Ruby on Rails application with a Postmark template, and does not provide any functionality for managing templates. Such functionality is already provided by Postmark's API and their Ruby client.

Add this line to your application's Gemfile:

gem 'postmark_mailer', github: 'scienceexchange/postmark_mailer'

And then execute:

$ bundle

Or install it yourself as:

$ gem install postmark_mailer

To start sending emails with Postmark's templates, you will need to set up some minimal configuration, and then make some changes to the mailer classes themselves.

In app/initializers/postmark_mailer.rb, add the following configuration block:

PostmarkMailer.configure do |config|
  config.api_key = YOUR_POSTMARK_API_KEY # required
  config.default_delivery_queue = :mailers # defaults to :default
end

To illustrate the usage of PostmarkMailer, let's take a look at a typical Rails mailer:

class MyCoolMailer < ActionMailer::Base
  def welcome(user)
    @user = user

    mail(
      to: @user.email,
      subject: 'Welcome to Our Product!'
    )
  end
end

The same mailer, using this gem would look like this:

class MyCoolMailer < PostmarkMailer::Base
  def welcome(user)
    mail(
      to: user.email,
      template_id: 123_456,
      template_model: {
        first_name: user.first_name
      }
    )
  end
end

Note the important changes:

• The mailer now inherits from PostmarkMailer::Base instead of ActionMailer::Base.
• You add template_id to your options hash. (This is required.)
• You add template_model to your options hash, which is an optional hash of whatever data you'd like to render in your template. (This is optional–in the unlikely event your template does not render any specific data, you can safely omit this option.)

The options you pass into the #mail method are ultimately passed on to the #deliver_with_template method provided by the Postmark API Ruby client, and so you'll want to refer to their documentation for a list of all the availabale options.

Because Postmark handles the templating and rendering, you no longer need the views for this mailer, so in this example, you could safely remove app/views/mailers/my_cool_mailer/welcome.html.erb.

Just as you would with a standard mailer, simply call:

MyCoolMailer.welcome(user).deliver_later

or, less optimally:

MyCoolMailer.welcome(user).deliver_now

In some mailers, you may wish to prevent delivery based on some business logic. For instance, if you offer email preferences to your users, you may want to check their preferences and prevent delivery if they've disabled email notifications.

To add mailer-wide logic, simply define a prevent_delivery? method in your mailer:

class MyCoolMailer < PostmarkMailer::Base
  def welcome(user)
    @user = user
    mail(
      to: @user.email,
      template_id: 123_456,
      template_model: {
        first_name: @user.first_name
      }
    )
  end

  private

  def prevent_delivery?
    # Substitute the line below with your own logic
    @user.all_emails_disabled?
  end
end

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 rubygems.org.

This gem is in it's infancy, so functionality is extremely limited at this point. Bug reports and pull requests are welcome on GitHub at https://github.com/scienceexchange/postmark_mailer.

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

PostmarkMailer is maintained by Science Exchange, the leading platform for outsourcing scientific research and development. Science Exchange is not affiliated with Postmark or Wildbit, LLC, and usage of Postmark is subject to their Terms of Service.

If you're interested helping improve the pace of scientific research, you should know that we're hiring!