This guide should provide you with all you need to get started in sending and receiving emails from and to your application, and many internals of Action Mailer. It also covers how to test your mailers.
Action Mailer allows you to send emails from your application using a mailer model and views. So, in Rails, emails are used by creating mailers that inherit from +ActionMailer::Base+ and live in +app/mailers+. Those mailers have associated views that appear alongside controller views in +app/views+.
Here is a quick explanation of the items presented in the preceding method. For a full list of all available options, please have a look further down at the Complete List of ActionMailer user-settable attributes section.
* <tt>default Hash</tt> - This is a hash of default values for any email you send, in this case we are setting the <tt>:from</tt> header to a value for all messages in this class, this can be overridden on a per email basis
* +mail+ - The actual email message, we are passing the <tt>:to</tt> and <tt>:subject</tt> headers in|
To login to the site, just follow this link: <%= @url %>.
Thanks for joining and have a great day!
</erb>
When you call the +mail+ method now, Action Mailer will detect the two templates (text and HTML) and automatically generate a <tt>multipart/alternative</tt> email.
There are three ways to achieve this. One is to send the email from the controller that sends the email, another is to put it in a +before_create+ callback in the user model, and the last one is to use an observer on the user model. Whether you use the second or third methods is up to you, but staying away from the first is recommended. Not because it's wrong, but because it keeps your controller clean, and keeps all logic related to the user model within the user model. This way, whichever way a user is created (from a web form, or from an API call, for example), we are guaranteed that the email will be sent.
You can make a +app/observers+ directory and Rails will automatically load it for you (Rails will automatically load anything in the +app+ directory as of version 3.0)
Notice how we call <tt>UserMailer.welcome_email(user)</tt>? Even though in the <tt>user_mailer.rb</tt> file we defined an instance method, we are calling the method_name +welcome_email(user)+ on the class. This is a peculiarity of Action Mailer.
NOTE: In previous versions of Rails, you would call +deliver_welcome_email+ or +create_welcome_email+ however in Rails 3.0 this has been deprecated in favour of just calling the method name itself.
* <tt>headers</tt> - Specifies any header on the email you want, you can pass a hash of header field names and value pairs, or you can call <tt>headers[:field_name] = 'value'</tt>
* <tt>attachments</tt> - Allows you to add attachments to your email, for example <tt>attachments['file-name.jpg'] = File.read('file-name.jpg')</tt>
* <tt>mail</tt> - Sends the actual email itself. You can pass in headers as a hash to the mail method as a parameter, mail will then create an email, either plain text, or multipart, depending on what email templates you have defined.
Adding attachments has been simplified in Action Mailer 3.0.
* Pass the file name and content and Action Mailer and the Mail gem will automatically guess the mime_type, set the encoding and create the attachment.
NOTE: Mail will automatically Base64 encode an attachment, if you want something different, pre encode your content and pass in the encoded content and encoding in a +Hash+ to the +attachments+ method.
Mailer views are located in the +app/views/name_of_mailer_class+ directory. The specific mailer view is known to the class because it's name is the same as the mailer method. So for example, in our example from above, our mailer view for the +welcome_email+ method will be in +app/views/user_mailer/welcome_email.html.erb+ for the HTML version and +welcome_email.text.erb+ for the plain text version.
Will render 'another_template.text.erb' and 'another_template.html.erb'. The render command is the same one used inside of Action Controller, so you can use all the same options, such as <tt>:text</tt> etc.
Just like controller views, you can also have mailer layouts. The layout name needs to be the same as your mailer, such as +user_mailer.html.erb+ and +user_mailer.text.erb+ to be automatically recognized by your mailer as a layout.
You can also pass in a <tt>:layout => 'layout_name'</tt> option to the render call inside the format block to specify different layouts for different actions:
<ruby>
class UserMailer < ActionMailer::Base
def welcome_email(user)
mail(:to => user.email) do |format|
format.html { render :layout => 'my_layout' }
format.text
end
end
end
</ruby>
Will render the HTML part using the <tt>my_layout.html.erb</tt> file and the text part with the usual <tt>user_mailer.text.erb</tt> file if it exists.
Unlike controllers, the mailer instance doesn't have any context about the incoming request so you'll need to provide the +:host+, +:controller+, and +:action+:
Email clients have no web context and so paths have no base URL to form complete web addresses. Thus, when using named routes only the "_url" variant makes sense.
It is also possible to set a default host that will be used in all mailers by setting the +:host+ option in the +ActionMailer::Base.default_url_options+ hash as follows:
Action Mailer will automatically send multipart emails if you have different templates for the same action. So, for our UserMailer example, if you have +welcome_email.text.erb+ and +welcome_email.html.erb+ in +app/views/user_mailer+, Action Mailer will automatically send a multipart email with the HTML and text versions setup as different parts.
The order of the parts getting inserted is determined by the <tt>:parts_order</tt> inside of the <tt>ActionMailer::Base.default</tt> method. If you want to explicitly alter the order, you can either change the <tt>:parts_order</tt> or explicitly render the parts in a different order:
The above will send a multipart email with an attachment, properly nested with the top level being <tt>mixed/multipart</tt> and the first part being a <tt>mixed/alternative</tt> containing the plain text and HTML email messages.
Receiving and parsing emails with Action Mailer can be a rather complex endeavour. Before your email reaches your Rails app, you would have had to configure your system to somehow forward emails to your app, which needs to be listening for that. So, to receive emails in your Rails app you'll need:
* Configure your email server to forward emails from the address(es) you would like your app to receive to +rails runner 'UserMailer.receive(STDIN.read)'+.
Once a method called +receive+ is defined in any mailer, Action Mailer will parse the raw incoming email into an email object, decode it, instantiate a new mailer, and pass the email object to the mailer +receive+ instance method. Here's an example:
The following configuration options are best made in one of the environment files (environment.rb, production.rb, etc...)
|template_root|Determines the base from which template references will be made.|
|logger|the logger is used for generating information on the mailing run if available. Can be set to nil for no logging. Compatible with both Ruby's own Logger and Log4r loggers.|
|smtp_settings|Allows detailed configuration for :smtp delivery method: :address - Allows you to use a remote mail server. Just change it from its default "localhost" setting. :port - On the off chance that your mail server doesn't run on port 25, you can change it. :domain - If you need to specify a HELO domain, you can do it here. :user_name - If your mail server requires authentication, set the username in this setting. :password - If your mail server requires authentication, set the password in this setting. :authentication - If your mail server requires authentication, you need to specify the authentication type here. This is a symbol and one of :plain, :login, :cram_md5.|
|sendmail_settings|Allows you to override options for the :sendmail delivery method. :location - The location of the sendmail executable. Defaults to /usr/sbin/sendmail. :arguments - The command line arguments. Defaults to -i -t.|
|raise_delivery_errors|Whether or not errors should be raised if the email fails to be delivered.|
|delivery_method|Defines a delivery method. Possible values are :smtp (default), :sendmail, and :test.|
|perform_deliveries|Determines whether deliver_* methods are actually carried out. By default they are, but this can be turned off to help functional testing.|
|deliveries|Keeps an array of all the emails sent out through the Action Mailer with delivery_method :test. Most useful for unit and functional testing.|
By default Action Mailer does not send emails in the test environment. They are just added to the +ActionMailer::Base.deliveries+ array.
Testing mailers normally involves two things: One is that the mail was queued, and the other one that the email is correct. With that in mind, we could test our example mailer from above like so:
In the test we send the email and store the returned object in the +email+ variable. We then ensure that it was sent (the first assert), then, in the second batch of assertions, we ensure that the email does indeed contain the what we expect.
