Action Mailer – Easy email delivery and testing

Action Mailer is a framework for designing email-service layers. These layers are used to consolidate code for sending out forgotten passwords, welcome wishes on signup, invoices for billing, and any other use case that requires a written notification to either a person or another system.

Additionally, an Action Mailer class can be used to process incoming email, such as allowing a weblog to accept new posts from an email (which could even have been sent from a phone).

Sending emails

The framework works by setting up all the email details, except the body, in methods on the service layer. Subject, recipients, sender, and timestamp are all set up this way. An example of such a method:

def signed_up(recipient)
  recipients recipient
  subject    "[Signed up] Welcome #{recipient}"
  from       "[email protected]"
  body       :recipient => recipient
end

The body of the email is created by using an Action View template (regular ERb) that has the content of the body hash parameter available as instance variables. So the corresponding body template for the method above could look like this:

Hello there, 

Mr. <%= @recipient %>

And if the recipient was given as “[email protected]”, the email generated would look like this:

Date: Sun, 12 Dec 2004 00:00:00 +0100
From: [email protected]
To: [email protected]
Subject: [Signed up] Welcome [email protected]

Hello there, 

Mr. [email protected]

You never actually call the instance methods like signed_up directly. Instead, you call class methods like deliver_* and create_* that are automatically created for each instance method. So if the signed_up method sat on ApplicationMailer, it would look like this:

ApplicationMailer.create_signed_up("[email protected]")  # => tmail object for testing
ApplicationMailer.deliver_signed_up("[email protected]") # sends the email
ApplicationMailer.new.signed_up("[email protected]")     # won't work!

Receiving emails

To receive emails, you need to implement a public instance method called receive that takes a tmail object as its single parameter. The Action Mailer framework has a corresponding class method, which is also called receive, that accepts a raw, unprocessed email as a string, which it then turns into the tmail object and calls the receive instance method.

Example:

class Mailman < ActionMailer::Base
  def receive(email)
    page = Page.find_by_address(email.to.first)
    page.emails.create(
      :subject => email.subject, :body => email.body
    )

    if email.has_attachments?
      for attachment in email.attachments
        page.attachments.create({ 
          :file => attachment, :description => email.subject
        })
      end
    end
  end
end

This Mailman can be the target for Postfix or other MTAs. In Rails, you would use the runner in the trivial case like this:

./script/runner 'Mailman.receive(STDIN.read)'

However, invoking Rails in the runner for each mail to be received is very resource intensive. A single instance of Rails should be run within a daemon if it is going to be utilized to process more than just a limited number of email.

Configuration

The Base class has the full list of configuration options. Here’s an example:

ActionMailer::Base.smtp_settings = {
  :address        => 'smtp.yourserver.com', # default: localhost
  :port           => '25',                  # default: 25
  :user_name      => 'user',
  :password       => 'pass',
  :authentication => :plain                 # :plain, :login or :cram_md5
}

Dependencies

Action Mailer requires that the Action Pack is either available to be required immediately or is accessible as a GEM.

Bundled software

tmail 0.10.8 by Minero Aoki released under LGPL Read more on i.loveruby.net/en/prog/tmail.html
Text::Format 0.63 by Austin Ziegler released under OpenSource Read more on www.halostatue.ca/ruby/Text__Format.html

Download

The latest version of Action Mailer can be found at

rubyforge.org/project/showfiles.php?group_id=361

Documentation can be found at

actionmailer.rubyonrails.org

Installation

You can install Action Mailer with the following command.

% [sudo] ruby install.rb

from its distribution directory.

License

Action Mailer is released under the MIT license.

Support

The Action Mailer homepage is www.rubyonrails.org. You can find the Action Mailer RubyForge page at rubyforge.org/projects/actionmailer. And as Jim from Rake says:

Feel free to submit commits or feature requests.  If you send a patch,
remember to update the corresponding unit tests.  If fact, I prefer
new feature to be submitted in the form of new unit tests.