Griddler

Receive emails in your Rails app

Griddler is a Rails engine (full plugin) that provides an endpoint for the SendGrid parse api, Cloudmailin parse api, Postmark parse api or Mandrill parse api Mailgun routes that hands off a built email object to a class implemented by you.

Tutorials

SendGrid has done a great tutorial on integrating Griddler with your application.
And of course, view our own blog post on the subject over at Giant Robots.

Installation

Add griddler to your application's Gemfile and run bundle install:

gem 'griddler'

A route is needed for the endpoint which receives POST messages. Currently, the route is automatically appended to the route table like so:

email_processor POST /email_processor(.:format)   griddler/emails#create

NOTE: This behavior is deprecated and will be removed by version 0.7.0 in favor of manually adding the route.

To manually add the route, in config/routes.rb you may either use the provided routing method mount_griddler or set the route explicitly. Examples:

# mount using default path
mount_griddler

# mount using a custom path
mount_griddler('/email/incoming')

# the "get off my lawn", DIY approach:
post '/email_processor' => 'griddler/emails#create'

Defaults

By default Griddler will look for a class to be created in your application called EmailProcessor with a class method implemented, named process, taking in one argument (presumably email). For example, in ./lib/email_processor.rb:

class EmailProcessor
  def self.process(email)
    # all of your application-specific code here - creating models,
    # processing reports, etc
  end
end

The contents of the email object passed into your process method is an object that responds to:

.to
.from
.cc
.subject
.body
.raw_text
.raw_html
.raw_body
.attachments
.headers
.raw_headers

Each of those has some sensible defaults.

.raw_body, .raw_headers, and .subject will contain the obvious values found in the email, the raw values from those fields.

.body will contain the full contents of the email body unless there is a line in the email containing the string -- Reply ABOVE THIS LINE --. In that case .body will contain everything before that line.

.to will contain an array of hashes. Each hash will have the following information of each recipient:

token: All the text before the email's "@". We've found that this is the most often used portion of the email address and consider it to be the token we'll key off of for interaction with our application.
host: All the text after the email's "@". This is important to filter the recipients sent to the application vs emails to other domains. More info below on the Upgrading to 0.5.0 section.
email: The email address of the recipient.
full: The whole recipient field. E.g, Some User <[email protected]>
name: The name of the recipient. E.g, Some User

.from will default to the email value of a hash like .to, and can be configured to return the full hash.

.cc behaves and can be configured like .to. If the adapter does not pass along a cc key then the headers will be parsed.

.attachments will contain an array of attachments as multipart/form-data files which can be passed off to attachment libraries like Carrierwave or Paperclip.

.headers will contain a hash of header names and values as parsed by the Mail gem. Headers will only be parsed if the adapter supports a headers option.

Configuration Options

An initializer can be created to control some of the options in Griddler. Defaults are shown below with sample overrides following. In config/initializers/griddler.rb:

Griddler.configure do |config|
  config.processor_class = EmailProcessor # MyEmailProcessor
  config.processor_method = :process # :custom_method
  config.to = :hash # :full, :email, :token
  config.cc = :email # :full, :hash, :token
  config.from = :email # :full, :token, :hash
  # :raw    => 'AppName <[email protected]>'
  # :email  => '[email protected]'
  # :token  => 's13.6b2d13dc6a1d33db7644'
  # :hash   => { raw: [...], email: [...], token: [...], host: [...], name: [...] }
  config.reply_delimiter = '-- REPLY ABOVE THIS LINE --'
  config.email_service = :sendgrid # :cloudmailin, :postmark, :mandrill, :mailgun
end

config.processor_class is the class Griddler will use to handle your incoming emails.
config.processor_method is the method Griddler will call on the processor class when handling your incoming emails.
config.reply_delimiter is the string searched for that will split your body.
config.to, config.cc and config.from are the format of the returned value for that address in the email object. :hash will return all options within a -- (surprise!) -- hash.
config.email_service tells Griddler which email service you are using. The supported email service options are :sendgrid (the default), :cloudmailin (expects multipart format), :postmark and :mandrill.

Testing In Your App

You may want to create a factory for when testing the integration of Griddler into your application. If you're using factory_girl this can be accomplished with the following sample factory.

factory :email, class: OpenStruct do
  # Assumes Griddler.configure.to is :hash (default)
  to [{ full: '[email protected]', email: '[email protected]', token: 'to_user', host: 'email.com', name: nil }]
  from '[email protected]'
  subject 'email subject'
  body 'Hello!'
  attachments {[]}

  trait :with_attachment do
    attachments {[
      ActionDispatch::Http::UploadedFile.new({
        filename: 'img.png',
        type: 'image/png',
        tempfile: File.new("#{File.expand_path File.dirname(__FILE__)}/fixtures/img.png")
      })
    ]}
  end
end

Bear in mind, if you plan on using the :with_attachment trait, that this example assumes your factories are in spec/factories.rb and you have an image file in spec/fixtures/.

To use it in your test(s) just build with email = build(:email) or email = build(:email, :with_attachment).

Adapters

Griddler::Email expects certain parameters to be in place for proper parsing to occur. When writing an adapter, ensure that the normalized_params method of your adapter returns a hash with these keys:

:to The recipient field
:from The sender field
:subject Email subject
:text The text body of the email
:html The html body of the email, nil or empty string if not present
:attachments (can be an empty array) Array of attachments to the email
:headers (optional) The raw headers of the email
:charsets (optional) A JSON string containing the character sets of the fields extracted from the message

Upgrading to Griddler 0.5.0

Because of an issue with the way Griddler handled recipients in the To header, a breaking change was introduced in Griddler 0.5.0 that requires a minor change to EmailProcessor or processor_class.

Previously, a single address was returned from Griddler::Email#to. Moving forward, this field will always be an array. Generally speaking, you will want to do something like this to handle the change:

# before
def initialize(email)
  @to = email.to
  @from = email.from
  @body = email.body
end

# after
def initialize(email)
  @to = pick_meaningful_recipient(email.to)
  @from = email.from
  @body = email.body
end

private

def pick_meaningful_recipient(recipients)
  recipients.find { |address| address =~ /@mydomain.com$/ }
end

Using Griddler with Mandrill

When adding a webhook in their administration panel, Mandrill will issue a HEAD request to check if the webhook is valid (see Adding Routes). If the HEAD request fails, Mandrill will not allow you to add the webhook. Since Griddler is only configured to handle POST requests, you will not be able to add the webhook as-is. To solve this, add a temporary route to your application that can handle the HEAD request:

# routes.rb
get "/email_processor", to: proc { [200, {}, ["OK"]] }, as: "mandrill_head_test_request"

Once you have correctly configured Mandrill, you can go ahead and delete this code.

More Information

Credits

Griddler was written by Caleb Thompson and Joel Oliveira.

Large portions of the codebase were extracted from thoughtbot's Trajectory.

The names and logos for thoughtbot are trademarks of thoughtbot, inc.