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A plugin for the Merb framework that allows you to send email from Merb application. It separates email composition and sending into micro MVC: you may have mail controllers that compose complex emails, emails have their own views and models (models use MailFactory library and non-persistable).


(sudo) gem install merb-mailer

This will automatically install dependencies:


In init.rb, include a dependency on merb-mailer. With versions of Merb earlier than 0.9.3, Merb::Mailer may raise a NameError when configuration is put into after_app_loads block. Put it to the very end of your init file and it should work. This problem does not exist in Git HEAD.

Using SMTP.

Merb::Mailer.config = {
  :host   => 'smtp.yourserver.com',
  :port   => '25',
  :user   => 'user',
  :pass   => 'pass',
  :auth   => :plain # :plain, :login, :cram_md5, the default is no auth
  :domain => "localhost.localdomain" # the HELO domain provided by the client to the server

Using Gmail SMTP.

  • require the gem "smtptls"
  • Use :text option instead of :body when deliver.

Configuration example for Gmail SMTP:

Merb::Mailer.config = {
  :host   => 'smtp.gmail.com',
  :port   => '587',
  :user   => 'user@gmail.com',
  :pass   => 'pass',
  :auth   => :plain

Use like:

m = Merb::Mailer.new :to      => 'foo@bar.com',
                     :from    => 'bar@foo.com',
                     :subject => 'Welcome to whatever!',
                     :text    => partial(:sometemplate)

Using Sendmail.

Merb::Mailer.config = {:sendmail_path => '/somewhere/odd'}
Merb::Mailer.delivery_method = :sendmail

Sending mail from controllers.

Merb mailer plugin has idea of separation of mailer logic from mailer templates to the point mailers in Merb have own tiny MVC architecture for emails. Your application controllers usually delegate email sending to mail controllers instead of doing it on their own.

To send your mail using mail controller you use send_mail method that takes mail controller class, action name, mail parameters and action parameters. params hash with action parameters mentioned above is accessible in mail controller's action.

def send_activation_email(person)
  send_mail PeopleMailer, :activation, {
    :from => "no-reply@example.com",
    :to => person.email,
    :subject => "Please activate your account"
  }, {
    :name => person.name

Mail parameters you can specify:

  • :to
  • :from
  • :replyto
  • :subject
  • :body
  • :cc

Example of Merb controller: class ProductDeliveryMailer < Merb::MailController def notify_on_delivery @delivery_info = params[:details] # you can access @delivery_info in rendered template render_mail end end

Mail templates are kept under app/views/mail controller name/template name just like with regular controllers. Content types in template name may be either text or html, like in app/mailers/views/user_mailer/hello.text.erb for the mailer controller above:

Hello <%= params[:name] %>

render_mail works similarly to render method. It takes either action as Symbol or Hash of template paths. Most of the times naming templates the same as your actions works so you can just use

class ResourceShortageMailer < Merb::MailController
  def notify_on_disk_space_shortage

and it will render app/mailers/views/resource_shortage_mailer/notify_on_disk_space_shortage.text.erb.

If you need to specify template path explicitly, you can do it for both text and html:

class ResourceShortageMailer < Merb::MailController
  def notify_on_disk_space_shortage
    render_mail :action => { :html => :hdd_space_shortage_detailed, :text => :hdd_space_shortage }

This will look for app/mailers/views/resource_shortage_mailer/hdd_space_shortage_detailed.html.erb for HTML and app/mailers/views/resource_shortage_mailer/hdd_space_shortage.text.erb for text.

See Merb::MailerMixin#render_mail documentation for more examples, this method has a lot of options how you can use it.

Using Merb mailer to send emails outside of controllers.

There are two ways of sending email with merb-mailer: using mail controllers and using just Merb::Mailer. Here is example of using Merb::Mailer to deliver emails from model hook.

class Person
  include DataMapper::Resource

  after :create, :deliver_activation_notification

  def deliver_activation_notification
    body_string = <<-EOS
      Please activate your account...
      :from    => "no-reply@webapp.com",
      :to      => self.email,
      :subject => "Activate your account",
      :body    => body_string

In this example we deliver signup activation email from model hook. Keep in mind that Merb::Mailer is a thin wrapper around MailFactory that provides several ways of sending emails. You can access plain text email body with text method of mailer and html body with html method, respectively.

Testing mailers.

A word of warning: merb-mailer does not raise exceptions when your template is not found. So if nothing gets rendered, check merb test environment log to make sure you have no warnings. If it is considered a bug, file a ticket to LightHouse.

Make sure you use test sending method so emails won't be sent on each tests run. Add this line to your test file:

Merb::Mailer.delivery_method = :test_send

Here is an example of helper to test mailers themselves:

def describe_mail(mailer, template, &block)
  describe "/#{mailer.to_s.downcase}/#{template}" do
    before :each do
      @mailer_class, @template = mailer, template
      @assigns = {}

    def deliver(send_params={}, mail_params={})
      mail_params = {:from => "from@example.com", :to => "to@example.com", :subject => "Please activate your account"}.merge(mail_params)
      @mailer_class.new(send_params).dispatch_and_deliver @template.to_sym, mail_params
      @mail = Merb::Mailer.deliveries.last

    instance_eval &block

Mailer controller specs may look like this then:

require File.join(File.dirname(__FILE__),'..','spec_helper')

describe_mail UserMailer, :hello do
  it "sends activation" do
    deliver :name => "Jamie"
    @mail.text.should == "Please activate your account, Jamie"

Most of mail controller specs verify delivered email headers like to, subject or body. To access deliveries you use Merb::Mailer.deliveries array.

It is recommended to clear it on test setup first:

require File.join(File.dirname(__FILE__),'..','spec_helper')

describe_mail UserMailer, :hello do
  before :each do

To do actual matching you can create a helper like this:

def last_delivered_email

and use it like this:

last_delivered_email.from.first.should == "no-reply@webapp.com"

Note that MailFactory that is used by merb-mailer under the covers returns headers as Arrays. This is why we used from.first in example above.