Action Mailer allows you to send email from your application using a mailer model and views.

Mailer Models

To use Action Mailer, you need to create a mailer model.

$ rails generate mailer Notifier

The generated model inherits from ActionMailer::Base. A mailer model defines methods used to generate an email message. In these methods, you can setup variables to be used in the mailer views, options on the mail itself such as the :from address, and attachments.

class Notifier < ActionMailer::Base
  default from: '',
          return_path: ''

  def welcome(recipient)
    @account = recipient
    mail(to: recipient.email_address_with_name,
         bcc: ["", "Order Watcher <>"])

Within the mailer method, you have access to the following methods:

  • attachments[]= - Allows you to add attachments to your email in an intuitive manner; attachments ='path/to/filename.png')

  • attachments.inline[]= - Allows you to add an inline attachment to your email in the same manner as attachments[]=

  • headers[]= - Allows you to specify any header field in your email such as headers['X-No-Spam'] = 'True'. Note, while most fields like To: From: can only appear once in an email header, other fields like X-Anything can appear multiple times. If you want to change a field that can appear multiple times, you need to set it to nil first so that Mail knows you are replacing it and not adding another field of the same name.

  • headers(hash) - Allows you to specify multiple headers in your email such as headers({'X-No-Spam' => 'True', 'In-Reply-To' => ''})

  • mail - Allows you to specify email to be sent.

The hash passed to the mail method allows you to specify any header that a Mail::Message will accept (any valid Email header including optional fields).

The mail method, if not passed a block, will inspect your views and send all the views with the same name as the method, so the above action would send the welcome.text.erb view file as well as the welcome.text.html.erb view file in a multipart/alternative email.

If you want to explicitly render only certain templates, pass a block:

mail(to: do |format|

The block syntax is also useful in providing information specific to a part:

mail(to: do |format|
  format.text(content_transfer_encoding: "base64")

Or even to render a special view:

mail(to: do |format|
  format.html { render "some_other_template" }

Mailer views

Like Action Controller, each mailer class has a corresponding view directory in which each method of the class looks for a template with its name.

To define a template to be used with a mailing, create an .erb file with the same name as the method in your mailer model. For example, in the mailer defined above, the template at app/views/notifier/welcome.text.erb would be used to generate the email.

Variables defined in the model are accessible as instance variables in the view.

Emails by default are sent in plain text, so a sample view for our model example might look like this:

Hi <%= %>,
Thanks for joining our service! Please check back often.

You can even use Action Pack helpers in these views. For example:

You got a new note!
<%= truncate(@note.body, length: 25) %>

If you need to access the subject, from or the recipients in the view, you can do that through message object:

You got a new note from <%= message.from %>!
<%= truncate(@note.body, length: 25) %>

Generating URLs

URLs can be generated in mailer views using url_for or named routes. Unlike controllers from Action Pack, the mailer instance doesn’t have any context about the incoming request, so you’ll need to provide all of the details needed to generate a URL.

When using url_for you’ll need to provide the :host, :controller, and :action:

<%= url_for(host: "", controller: "welcome", action: "greeting") %>

When using named routes you only need to supply the :host:

<%= users_url(host: "") %>

You should use the named_route_url style (which generates absolute URLs) and avoid using the named_route_path style (which generates relative URLs), since clients reading the mail will have no concept of a current URL from which to determine a relative path.

It is also possible to set a default host that will be used in all mailers by setting the :host option as a configuration option in config/application.rb:

config.action_mailer.default_url_options = { host: "" }

When you decide to set a default :host for your mailers, then you need to make sure to use the only_path: false option when using url_for. Since the url_for view helper will generate relative URLs by default when a :host option isn’t explicitly provided, passing only_path: false will ensure that absolute URLs are generated.

Sending mail

Once a mailer action and template are defined, you can deliver your message or create it and save it for delivery later:

Notifier.welcome(david).deliver # sends the email
mail = Notifier.welcome(david)  # => a Mail::Message object
mail.deliver                    # sends the email

You never instantiate your mailer class. Rather, you just call the method you defined on the class itself.

Multipart Emails

Multipart messages can also be used implicitly because Action Mailer will automatically detect and use multipart templates, where each template is named after the name of the action, followed by the content type. Each such detected template will be added as a separate part to the message.

For example, if the following templates exist:

  • signup_notification.text.erb

  • signup_notification.text.html.erb

  • signup_notification.text.xml.builder

  • signup_notification.text.yaml.erb

Each would be rendered and added as a separate part to the message, with the corresponding content type. The content type for the entire message is automatically set to multipart/alternative, which indicates that the email contains multiple different representations of the same email body. The same instance variables defined in the action are passed to all email templates.

Implicit template rendering is not performed if any attachments or parts have been added to the email. This means that you’ll have to manually add each part to the email and set the content type of the email to multipart/alternative.


Sending attachment in emails is easy:

class ApplicationMailer < ActionMailer::Base
  def welcome(recipient)
    attachments['free_book.pdf'] ='path/to/file.pdf')
    mail(to: recipient, subject: "New account information")

Which will (if it had both a welcome.text.erb and welcome.text.html.erb template in the view directory), send a complete multipart/mixed email with two parts, the first part being a multipart/alternative with the text and HTML email parts inside, and the second being a application/pdf with a Base64 encoded copy of the file.pdf book with the filename free_book.pdf.

If you need to send attachments with no content, you need to create an empty view for it, or add an empty body parameter like this:

class ApplicationMailer < ActionMailer::Base
  def welcome(recipient)
    attachments['free_book.pdf'] ='path/to/file.pdf')
    mail(to: recipient, subject: "New account information", body: "")

Inline Attachments

You can also specify that a file should be displayed inline with other HTML. This is useful if you want to display a corporate logo or a photo.

class ApplicationMailer < ActionMailer::Base
  def welcome(recipient)
    attachments.inline['photo.png'] ='path/to/photo.png')
    mail(to: recipient, subject: "Here is what we look like")

And then to reference the image in the view, you create a welcome.html.erb file and make a call to image_tag passing in the attachment you want to display and then call url on the attachment to get the relative content id path for the image source:

<h1>Please Don't Cringe</h1>

<%= image_tag attachments['photo.png'].url -%>

As we are using Action View’s image_tag method, you can pass in any other options you want:

<h1>Please Don't Cringe</h1>

<%= image_tag attachments['photo.png'].url, alt: 'Our Photo', class: 'photo' -%>

Observing and Intercepting Mails

Action Mailer provides hooks into the Mail observer and interceptor methods. These allow you to register classes that are called during the mail delivery life cycle.

An observer class must implement the :delivered_email(message) method which will be called once for every email sent after the email has been sent.

An interceptor class must implement the :delivering_email(message) method which will be called before the email is sent, allowing you to make modifications to the email before it hits the delivery agents. Your class should make any needed modifications directly to the passed in Mail::Message instance.

Default Hash

Action Mailer provides some intelligent defaults for your emails, these are usually specified in a default method inside the class definition:

class Notifier < ActionMailer::Base
  default sender: ''

You can pass in any header value that a Mail::Message accepts. Out of the box, ActionMailer::Base sets the following:

  • mime_version: "1.0"

  • charset: "UTF-8",

  • content_type: "text/plain",

  • parts_order: [ "text/plain", "text/enriched", "text/html" ]

parts_order and charset are not actually valid Mail::Message header fields, but Action Mailer translates them appropriately and sets the correct values.

As you can pass in any header, you need to either quote the header as a string, or pass it in as an underscored symbol, so the following will work:

class Notifier < ActionMailer::Base
  default 'Content-Transfer-Encoding' => '7bit',
          content_description: 'This is a description'

Finally, Action Mailer also supports passing Proc objects into the default hash, so you can define methods that evaluate as the message is being generated:

class Notifier < ActionMailer::Base
  default 'X-Special-Header' => { my_method }


    def my_method
      'some complex call'

Note that the proc is evaluated right at the start of the mail message generation, so if you set something in the defaults using a proc, and then set the same thing inside of your mailer method, it will get over written by the mailer method.

It is also possible to set these default options that will be used in all mailers through the default_options= configuration in config/application.rb:

config.action_mailer.default_options = { from: "" }


You can specify callbacks using before_action and after_action for configuring your messages. This may be useful, for example, when you want to add default inline attachments for all messages sent out by a certain mailer class:

class Notifier < ActionMailer::Base
  before_action :add_inline_attachment!

  def welcome


    def add_inline_attachment!
      attachments.inline["footer.jpg"] ='/path/to/filename.jpg')

Callbacks in ActionMailer are implemented using AbstractController::Callbacks, so you can define and configure callbacks in the same manner that you would use callbacks in classes that inherit from ActionController::Base.

Note that unless you have a specific reason to do so, you should prefer using before_action rather than after_action in your ActionMailer classes so that headers are parsed properly.

Configuration options

These options are specified on the class level, like ActionMailer::Base.raise_delivery_errors = true

  • default_options - You can pass this in at a class level as well as within the class itself as per the above section.

  • 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 (will send the password in the clear), :login (will send password Base64 encoded) or :cram_md5 (combines a Challenge/Response mechanism to exchange information and a cryptographic Message Digest 5 algorithm to hash important information)

    • :enable_starttls_auto - When set to true, detects if STARTTLS is enabled in your SMTP server and starts to use it.

    • :openssl_verify_mode - When using TLS, you can set how OpenSSL checks the certificate. This is really useful if you need to validate a self-signed and/or a wildcard certificate. You can use the name of an OpenSSL verify constant (‘none’, ‘peer’, ‘client_once’, ‘fail_if_no_peer_cert’) or directly the constant (OpenSSL::SSL::VERIFY_NONE, OpenSSL::SSL::VERIFY_PEER, …).

  • 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 with -f sender@address added automatically before the message is sent.

  • file_settings - Allows you to override options for the :file delivery method.

    • :location - The directory into which emails will be written. Defaults to the application tmp/mails.

  • 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, :test, and :file. Or you may provide a custom delivery method object e.g. MyOwnDeliveryMethodClass. See the Mail gem documentation on the interface you need to implement for a custom delivery agent.

  • perform_deliveries - Determines whether emails are actually sent from Action Mailer when you call .deliver on an mail message or on an Action Mailer method. This is on by default but can be turned off to aid in 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.

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July 24, 2008
8 thanks

render template file different from your action (method) name

In some cases you have to avoid rails magic that uses template names named as your ActionMailer method.

rails magic

def daily_notification
  # ...
# will look for daily_notification.erb

def weekly_notification
  # ...
# will look for weekly_notification.erb

your case

Just give necessary value to @template instance variable.

def setup
  # ...
  @template = 'notification'

def daily_notification
  # ...
# will look for notification.erb

def weekly_notification
  # ...
# will look for notification.erb
March 21, 2009
7 thanks

Use helpers in your ActionMailer views

It’s very easy to give your mailer access to helpers:

# Let your mailer user the ApplicationHelper methods
class MyMailer < ActionMailer::Base
  helper :application
July 30, 2008
7 thanks

Using gmail SMTP server to send mail

First you would need to sign up with Google Apps, which is a very painless process:

Next you need to install a plugin that will allow ActionMailer to make a secure connection to google:

script/plugin install git://

We need this due to transport layer security used by google.

Lastly all you need to do is place this in your environment.rb file and modify it to your settings:

ActionMailer::Base.smtp_settings = {
 :address => "",
 :port => 587,
 :domain => "",
 :authentication => :plain,
 :user_name => "google_username",
 :password => "password"
May 8, 2009
2 thanks

Using gmail SMTP server to send mail

If you’re running Rails >= 2.2.1 [RC2] and Ruby 1.8.7, you don’t need plugin below. Ruby 1.8.7 supports SMTP TLS and Rails 2.2.1 ships with an option to enable it if you’re running Ruby 1.8.7.

All You need to do is:

ActionMailer::Base.smtp_settings = {
  :enable_starttls_auto => true
November 5, 2008 - (v1.0.0 - v2.1.0)
1 thank

james' note incorrect

The render method in ActionMailer is infact a private method, in all versions (including the new Rails 2.2).

However, spectators note about @template works well. Thanks.

August 10, 2009
0 thanks

Content type for emails with attachments

Be aware that if you want to send emails with attachments, you probably want to use the content type multipart/mixed for the overall email.

The MIME time multipart/alternative is intended for emails where each part is a different representation of the same message.

After following the 2.3.2 documentation we used multipart/alternative to attach files to our mails, however this then caused Hotmail to ignore the attachments. It turns out it thought they were all alternative versions of the HTML content (which it could already display, so the alternatives weren’t necessary)

July 25, 2008 - (v1.0.0 - v2.1.0)
0 thanks

render template file different from your action (method) name - alternative

Alternative ways to render templates for actions

# Renders the template for foo (foo.html.erb, foo.haml.erb, foo.text.html.haml, whatever :P)
def foo

# Renders the template that would be rendered in foo
# (but without the foo controller action being invoked)
def bar
  render :action => 'foo'

# Similar to what bar does, but render's a specifically named template
def roar
  render :template => 'foo'

# Similar to what roar does, but render's a template
# from outside of the current controller's views directory
def boo
  render :template => 'global/something'
April 27, 2010
0 thanks

smtp syntax error 555 5.5.2

If You’re seeing a Net::SMTPFatalError (555 5.5.2 Syntax error ...) than You should check the email’s from header ! You probably have brackets while calling the from attribute setter :

Works in Rails < 2.3.3

def signup_notification(recipient)
  recipients      recipient.email_address_with_name
  subject         "New account information"
  from            %("My App" <>)

Works in Rails 2.3.5

def signup_notification(recipient)
  recipients      recipient.email_address_with_name
  subject         "New account information"
  from            '' # no <> brackets !

in Rails 2.3.3 the from email address will get wrapped with angle brackets, thus it must not have them within the address.

November 5, 2008
0 thanks

re: james' note incorrect

kieran is correct, my note is incorrect, it was not meant for ActionMailer::Base

November 12, 2011 - (<= v2.3.8)
0 thanks

Specify attachment names

If you want to give your attachment a name, you can do this:

attachment :filename => 'my_file.txt', :body =>'/var/null')

It will appear to the recipient as a file named “my_file.txt” rather than something awful like “noname 1”.

August 22, 2012 - (v3.2.8)
0 thanks

Using Amazon Simple Email Service with ActionMailer

First of all, get all the necessary SES credentials and verify your email address.

Then, just edit your config/environments/*.rb files:

config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
    address: '',
    user_name: 'your-ses-smtp-user-name',
    password: 'your-ses-smtp-password',
    authentication: :login,
    enable_starttls_auto: true

And that’s it!