This guide should provide you with all you need to get started in sending and receiving emails from/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 models that inherit from +ActionMailer::Base+ that live alongside other models in +app/models+. Those models have associated views that appear alongside controller views in +app/views+.
Here is a quick explanation of the options 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.
The keys of the hash passed to +body+ become instance variables in the view. Thus, in our example the mailer view will have a +@user+ and a +@url+ instance variables available.
Had we wanted to send text-only emails, the file would have been called +welcome_email.text.plain.erb+. Rails sets the content type of the email to be the one in the filename.
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.
Let's see how we would go about wiring it up using an observer:
Notice how we call +deliver_welcome_email+? In Action Mailer we send emails by calling +deliver_<method_name>+. In UserMailer, we defined a method called +welcome_email+, and so we deliver the email by calling +deliver_welcome_email+. The next section will go through how Action Mailer achieves this.
So how does Action Mailer understand this +deliver_welcome_email+ call? If you read the documentation (http://api.rubyonrails.org/files/vendor/rails/actionmailer/README.html), you will find this in the "Sending Emails" section:
You never instantiate your mailer class. Rather, your delivery instance methods are automatically wrapped in class methods that start with the word +deliver_+ followed by the name of the mailer method that you would like to deliver.
when /^create_([_a-z]\w*)/ then new($1, *parameters).mail
when /^deliver_([_a-z]\w*)/ then new($1, *parameters).deliver!
when "new" then nil
else super
end
end
</ruby>
Hence, if the method name starts with +deliver_+ followed by any combination of lowercase letters or underscore, +method_missing+ calls +new+ on your mailer class (+UserMailer+ in our example above), sending the combination of lower case letters or underscore, along with the parameters. The resulting object is then sent the +deliver!+ method, which well... delivers it.
|body| The body of the email. This is either a hash (in which case it specifies the variables to pass to the template when it is rendered), or a string, in which case it specifies the actual body of the message|
|charset| The charset to use for the email. This defaults to the +default_charset+ specified for ActionMailer::Base.|
|content_type| The content type for the email. This defaults to "text/plain" but the filename may specify it|
|from| The from address of the email|
|reply_to| The address (if different than the "from" address) to direct replies to this email|
|headers| Additional headers to be added to the email|
|implicit_parts_order| The order in which parts should be sorted, based on the content type. This defaults to the value of +default_implicit_parts_order+|
|mime_version| Defaults to "1.0", but may be explicitly given if needed|
|recipient| The recipient addresses of the email, either as a string (for a single address) or an array of strings (for multiple addresses)|
|sent_on| The timestamp on which the message was sent. If unset, the header will be set by the delivery agent|
|subject| The subject of the email|
|template| The template to use. This is the "base" template name, without the extension or directory, and may be used to have multiple mailer methods share the same template|
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.text.html.erb+ for the HTML version and +welcome_email.text.plain.erb+ for the plain text version.
Just like controller views, you can also have mailer layouts. The layout name needs to end in "_mailer" to be automatically recognized by your mailer as a layout. So in our UserMailer example, we need to call our layout +user_mailer.text.(html|plain).erb+. In order to use a different file just use:
URLs can be generated in mailer views using +url_for+ or named routes.
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.
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.plain.erb+ and +welcome_email.text.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.
Once you use the +attachment+ method, ActionMailer will no longer automagically use the correct template based on the filename, nor will it properly order the alternative parts. You must declare which template you are using for each content type via the +part+ method. And you must declare these templates in the proper order.
In the following example, there would be two template files, +welcome_email_html.erb+ and +welcome_email_plain.erb+ in the +app/views/user_mailer+ folder. The +text/plain+ part must be listed first for full compatibility with email clients. If +text/plain+ is listed after +text/html+, some clients may display both the HTML and plain text versions of the email. The text alternatives alone must be enclosed in a +multipart/alternative+ part. Do not set the entire message's +content_type+ to +multipart/alternative+ or some email clients may ignore the display of attachments such as PDF's.
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:
2. Configure your email server to forward emails from the address(es) you would like your app to receive to +/path/to/app/script/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:
Action Mailer classes have 4 helper methods available to them:
|add_template_helper(helper_module)|Makes all the (instance) methods in the helper module available to templates rendered through this controller.|
|helper(*args, &block)| Declare a helper: helper :foo requires 'foo_helper' and includes FooHelper in the template class. helper FooHelper includes FooHelper in the template class. helper { def foo() "#{bar} is the very best" end } evaluates the block in the template class, adding method foo. helper(:three, BlindHelper) { def mice() 'mice' end } does all three. |
|helper_method| Declare a controller method as a helper. For example, helper_method :link_to def link_to(name, options) ... end makes the link_to controller method available in the view.|
|helper_attr| Declare a controller attribute as a helper. For example, helper_attr :name attr_accessor :name makes the name and name= controller methods available in the view. The is a convenience wrapper for helper_method.|
h3. Action Mailer Configuration
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.|
|default_charset|The default charset used for the body and to encode the subject. Defaults to UTF-8. You can also pick a different charset from inside a method with charset.|
|default_content_type|The default content type used for the main part of the message. Defaults to "text/plain". You can also pick a different content type from inside a method with content_type.|
|default_mime_version|The default mime version used for the message. Defaults to 1.0. You can also pick a different value from inside a method with mime_version.|
|default_implicit_parts_order|When a message is built implicitly (i.e. multiple parts are assembled from templates which specify the content type in their filenames) this variable controls how the parts are ordered. Defaults to ["text/html", "text/enriched", "text/plain"]. Items that appear first in the array have higher priority in the mail client and appear last in the mime encoded message. You can also pick a different order from inside a method with implicit_parts_order.|
First you must install the "action_mailer_tls":http://github.com/openrain/action_mailer_tls plugin, then all you have to do is configure Action Mailer:
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.
