This guide provides 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.
After reading this guide, you will know:
How to send and receive email within a Rails application.
How to generate and edit an Action Mailer class and mailer view.
How to configure Action Mailer for your environment.
How to test your Action Mailer classes.
Action Mailer allows you to send emails from your application using mailer
classes and views. Mailers work very similarly to controllers. They inherit
from ActionMailer::Base
and live in app/mailers
,
and they have associated views that appear in app/views
.
This section will provide a step-by-step guide to creating a mailer and its views.
$ rails generate mailer UserMailer create app/mailers/user_mailer.rb invoke erb create app/views/user_mailer invoke test_unit create test/mailers/user_mailer_test.rb
As you can see, you can generate mailers just like you use other generators with Rails. Mailers are conceptually similar to controllers, and so we get a mailer, a directory for views, and a test.
If you didn't want to use a generator, you could create your own file
inside of app/mailers, just make sure that it inherits from
ActionMailer::Base
:
class MyMailer < ActionMailer::Base end
Mailers are very similar to Rails controllers. They also have methods called “actions” and use views to structure the content. Where a controller generates content like HTML to send back to the client, a Mailer creates a message to be delivered via email.
app/mailers/user_mailer.rb
contains an empty mailer:
class UserMailer < ActionMailer::Base default from: 'from@example.com' end
Let's add a method called welcome_email
, that will send an
email to the user's registered email address:
class UserMailer < ActionMailer::Base default from: 'notifications@example.com' def welcome_email(user) @user = user @url = 'http://example.com/login' mail(to: @user.email, subject: 'Welcome to My Awesome Site') end end
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 Action Mailer user-settable attributes section.
default Hash
- This is a hash of default values for any email
you send from this mailer. In this case we are setting the
:from
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
:to
and :subject
headers in.
Just like controllers, any instance variables we define in the method become available for use in the views.
Create a file called welcome_email.html.erb
in
app/views/user_mailer/
. This will be the template used for the
email, formatted in HTML:
<!DOCTYPE html> <html> <head> <meta content='text/html; charset=UTF-8' http-equiv='Content-Type' /> </head> <body> <h1>Welcome to example.com, <%= @user.name %></h1> <p> You have successfully signed up to example.com, your username is: <%= @user.login %>.<br/> </p> <p> To login to the site, just follow this link: <%= @url %>. </p> <p>Thanks for joining and have a great day!</p> </body> </html>
Let's also make a text part for this email. Not all clients prefer HTML
emails, and so sending both is best practice. To do this, create a file
called welcome_email.text.erb
in
app/views/user_mailer/
:
Welcome to example.com, <%= @user.name %> =============================================== You have successfully signed up to example.com, your username is: <%= @user.login %>. To login to the site, just follow this link: <%= @url %>. Thanks for joining and have a great day!
When you call the mail
method now, Action Mailer will detect
the two templates (text and HTML) and automatically generate a
multipart/alternative
email.
Mailers are really just another way to render a view. Instead of rendering a view and sending out the HTTP protocol, they are just sending it out through the Email protocols instead. Due to this, it makes sense to just have your controller tell the Mailer to send an email when a user is successfully created.
Setting this up is painfully simple.
First, let's create a simple User
scaffold:
$ rails generate scaffold user name email login $ rake db:migrate
Now that we have a user model to play with, we will just edit the
app/controllers/users_controller.rb
make it instruct the
UserMailer to deliver an email to the newly created user by editing the
create action and inserting a call to UserMailer.welcome_email
right after the user is successfully saved:
class UsersController < ApplicationController # POST /users # POST /users.json def create @user = User.new(params[:user]) respond_to do |format| if @user.save # Tell the UserMailer to send a welcome Email after save UserMailer.welcome_email(@user).deliver format.html { redirect_to(@user, notice: 'User was successfully created.') } format.json { render json: @user, status: :created, location: @user } else format.html { render action: 'new' } format.json { render json: @user.errors, status: :unprocessable_entity } end end end end
The method welcome_email
returns a Mail::Message
object which can then just be told deliver
to send itself out.
Action Mailer handles the auto encoding of multibyte characters inside of headers and bodies.
For more complex examples such as defining alternate character sets or self-encoding text first, please refer to the Mail library.
There are just three methods that you need to send pretty much any email message:
headers
- Specifies any header on the email you want. You can
pass a hash of header field names and value pairs, or you can call
headers[:field_name] = 'value'
.
attachments
- Allows you to add attachments to your email. For
example, attachments['file-name.jpg'] =
File.read('file-name.jpg')
.
mail
- 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.
Action Mailer makes it very easy to add attachments.
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.
attachments['filename.jpg'] = File.read('/path/to/filename.jpg')
When the mail
method will be triggered, it will send a
multipart email with an attachment, properly nested with the top level
being multipart/mixed
and the first part being a
multipart/alternative
containing the plain text and HTML
email messages.
NOTE: Mail will automatically Base64 encode an attachment. If you want
something different, encode your content and pass in the encoded content
and encoding in a Hash
to the attachments
method.
Pass the file name and specify headers and content and Action Mailer and Mail will use the settings you pass in.
encoded_content = SpecialEncode(File.read('/path/to/filename.jpg')) attachments['filename.jpg'] = {mime_type: 'application/x-gzip', encoding: 'SpecialEncoding', content: encoded_content }
NOTE: If you specify an encoding, Mail will assume that your content is already encoded and not try to Base64 encode it.
Action Mailer 3.0 makes inline attachments, which involved a lot of hacking in pre 3.0 versions, much simpler and trivial as they should be.
First, to tell Mail to turn an attachment into an inline attachment, you
just call #inline
on the attachments method within your
Mailer:
def welcome attachments.inline['image.jpg'] = File.read('/path/to/image.jpg') end
Then in your view, you can just reference attachments
as a
hash and specify which attachment you want to show, calling
url
on it and then passing the result into the
image_tag
method:
<p>Hello there, this is our image</p> <%= image_tag attachments['image.jpg'].url %>
As this is a standard call to image_tag
you can pass in an
options hash after the attachment URL as you could for any other image:
<p>Hello there, this is our image</p> <%= image_tag attachments['image.jpg'].url, alt: 'My Photo', class: 'photos' %>
It is possible to send email to one or more recipients in one email (e.g.,
informing all admins of a new signup) by setting the list of emails to the
:to
key. The list of emails can be an array of email addresses
or a single string with the addresses separated by commas.
class AdminMailer < ActionMailer::Base default to: Proc.new { Admin.pluck(:email) }, from: 'notification@example.com' def new_registration(user) @user = user mail(subject: "New User Signup: #{@user.email}") end end
The same format can be used to set carbon copy (Cc:) and blind carbon copy
(Bcc:) recipients, by using the :cc
and :bcc
keys
respectively.
Sometimes you wish to show the name of the person instead of just their
email address when they receive the email. The trick to doing that is to
format the email address in the format "Full Name
<email>"
.
def welcome_email(user) @user = user email_with_name = "#{@user.name} <#{@user.email}>" mail(to: email_with_name, subject: 'Welcome to My Awesome Site') end
Mailer views are located in the app/views/name_of_mailer_class
directory. The specific mailer view is known to the class because its name
is the same as the mailer method. 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.
To change the default mailer view for your action you do something like:
class UserMailer < ActionMailer::Base default from: 'notifications@example.com' def welcome_email(user) @user = user @url = 'http://example.com/login' mail(to: @user.email, subject: 'Welcome to My Awesome Site', template_path: 'notifications', template_name: 'another') end end
In this case it will look for templates at
app/views/notifications
with name another
. You
can also specify an array of paths for template_path
, and they
will be searched in order.
If you want more flexibility you can also pass a block and render specific templates or even render inline or text without using a template file:
class UserMailer < ActionMailer::Base default from: 'notifications@example.com' def welcome_email(user) @user = user @url = 'http://example.com/login' mail(to: @user.email, subject: 'Welcome to My Awesome Site') do |format| format.html { render 'another_template' } format.text { render text: 'Render text' } end end end
This will render the template 'another_template.html.erb' for the
HTML part and use the rendered text for the text part. The render command
is the same one used inside of Action Controller, so you can use all the
same options, such as :text
, :inline
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.
In order to use a different file, call layout
in your mailer:
class UserMailer < ActionMailer::Base layout 'awesome' # use awesome.(html|text).erb as the layout end
Just like with controller views, use yield
to render the view
inside the layout.
You can also pass in a layout: 'layout_name'
option to
the render call inside the format block to specify different layouts for
different actions:
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
Will render the HTML part using the my_layout.html.erb
file
and the text part with the usual user_mailer.text.erb
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
parameter yourself.
As the :host
usually is consistent across the application you
can configure it globally in config/application.rb
:
config.action_mailer.default_url_options = { host: 'example.com' }
url_for
¶ ↑You need to pass the only_path: false
option when using
url_for
. This will ensure that absolute URLs are generated
because the url_for
view helper will, by default, generate
relative URLs when a :host
option isn't explicitly
provided.
<%= url_for(controller: 'welcome', action: 'greeting', only_path: false) %>
If you did not configure the :host
option globally make sure
to pass it to url_for
.
<%= url_for(host: 'example.com', controller: 'welcome', action: 'greeting') %>
NOTE: When you explicitly pass the :host
Rails will always
generate absolute URLs, so there is no need to pass only_path:
false
.
Email clients have no web context and so paths have no base URL to form complete web addresses. Thus, you should always use the “_url” variant of named route helpers.
If you did not configure the :host
option globally make sure
to pass it to the url helper.
<%= user_url(@user, host: 'example.com') %>
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
:parts_order
inside of the
ActionMailer::Base.default
method.
If you wish to override the default delivery options (e.g. SMTP
credentials) while delivering emails, you can do this using
delivery_method_options
in the mailer action.
class UserMailer < ActionMailer::Base def welcome_email(user, company) @user = user @url = user_url(@user) delivery_options = { user_name: company.smtp_user, password: company.smtp_password, address: company.smtp_host } mail(to: @user.email, subject: "Please see the Terms and Conditions attached", delivery_method_options: delivery_options) end end
There may be cases in which you want to skip the template rendering step
and supply the email body as a string. You can achieve this using the
:body
option. In such cases don't forget to add the
:content_type
option. Rails will default to
text/plain
otherwise.
class UserMailer < ActionMailer::Base def welcome_email(user, email_body) mail(to: user.email, body: email_body, content_type: "text/html", subject: "Already rendered!") end end
Receiving and parsing emails with Action Mailer can be a rather complex endeavor. 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 to:
Implement a receive
method in your mailer.
Configure your email server to forward emails from the address(es) you
would like your app to receive to /path/to/app/bin/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:
class UserMailer < 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? email.attachments.each do |attachment| page.attachments.create({ file: attachment, description: email.subject }) end end end end
Action Mailer allows for you to specify a before_action
,
after_action
and around_action
.
Filters can be specified with a block or a symbol to a method in the mailer class similar to controllers.
You could use a before_action
to populate the mail object with
defaults, delivery_method_options or insert default headers and
attachments.
You could use an after_action
to do similar setup as a
before_action
but using instance variables set in your mailer
action.
class UserMailer < ActionMailer::Base after_action :set_delivery_options, :prevent_delivery_to_guests, :set_business_headers def feedback_message(business, user) @business = business @user = user mail end def campaign_message(business, user) @business = business @user = user end private def set_delivery_options # You have access to the mail instance, # @business and @user instance variables here if @business && @business.has_smtp_settings? mail.delivery_method.settings.merge!(@business.smtp_settings) end end def prevent_delivery_to_guests if @user && @user.guest? mail.perform_deliveries = false end end def set_business_headers if @business headers["X-SMTPAPI-CATEGORY"] = @business.code end end end
Mailer Filters abort further processing if body is set to a non-nil value.
Action Mailer now just inherits from AbstractController
, so
you have access to the same generic helpers as you do in Action Controller.
The following configuration options are best made in one of the environment files (environment.rb, production.rb, etc…)
| Configuration | Description | |—————|————-|
|logger
|Generates 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:<ul><li>:address
- Allows you to use a
remote mail server. Just change it from its default “localhost”
setting.</li><li>:port
- On the off chance that
your mail server doesn't run on port 25, you can change
it.</li><li>:domain
- If you need to specify a
HELO domain, you can do it
here.</li><li>:user_name
- If your mail server
requires authentication, set the username in this
setting.</li><li>:password
- If your mail server
requires authentication, set the password in this
setting.</li><li>: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
.</li><li>:enable_starttls_auto
- Set this to false
if there is a problem with your server
certificate that you cannot resolve.</li></ul>|
|sendmail_settings
|Allows you to override options for the
:sendmail
delivery
method.<ul><li>:location
- The location of the
sendmail executable. Defaults to
/usr/sbin/sendmail
.</li><li>:arguments
- The command line arguments to be passed to sendmail. Defaults to -i
-t
.</li></ul>|
|raise_delivery_errors
|Whether or not errors should be raised
if the email fails to be delivered. This only works if the external email
server is configured for immediate delivery.|
|delivery_method
|Defines a delivery method. Possible values
are :smtp
(default), :sendmail
,
:file
and :test
.|
|perform_deliveries
|Determines whether deliveries are actually
carried out when the deliver
method is invoked on the Mail
message. 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_options
|Allows you to
set default values for the mail
method options
(:from
, :reply_to
, etc.).|
For a complete writeup of possible configurations see the Action Mailer section in our Configuring Rails Applications guide.
An example would be adding the following to your appropriate
config/environments/$RAILS_ENV.rb
file:
config.action_mailer.delivery_method = :sendmail # Defaults to: # config.action_mailer.sendmail_settings = { # location: '/usr/sbin/sendmail', # arguments: '-i -t' # } config.action_mailer.perform_deliveries = true config.action_mailer.raise_delivery_errors = true config.action_mailer.default_options = {from: 'no-replay@example.com'}
As Action Mailer now uses the Mail gem, this becomes as simple as adding to
your config/environments/$RAILS_ENV.rb
file:
config.action_mailer.delivery_method = :smtp config.action_mailer.smtp_settings = { address: 'smtp.gmail.com', port: 587, domain: 'example.com', user_name: '<username>', password: '<password>', authentication: 'plain', enable_starttls_auto: true }
You can find detailed instructions on how to test your mailers in the testing guide.
There are situations where you need to edit an email before it's delivered. Fortunately Action Mailer provides hooks to intercept every email. You can register an interceptor to make modifications to mail messages right before they are handed to the delivery agents.
class SandboxEmailInterceptor def self.delivering_email(message) message.to = ['sandbox@example.com'] end end
Before the interceptor can do its job you need to register it with the
Action Mailer framework. You can do this in an initializer file
config/initializers/sandbox_email_interceptor.rb
ActionMailer::Base.register_interceptor(SandboxEmailInterceptor) if Rails.env.staging?
NOTE: The example above uses a custom environment called “staging” for a production like server but for testing purposes. You can read Creating Rails environments for more information about custom Rails environments.