Action Mailer Basics¶ ↑
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.
Introduction¶ ↑
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
.
Sending Emails¶ ↑
This section will provide a step-by-step guide to creating a mailer and its views.
Walkthrough to Generating a Mailer¶ ↑
Create the Mailer¶ ↑
$ bin/rails generate mailer UserMailer create app/mailers/user_mailer.rb create app/mailers/application_mailer.rb invoke erb create app/views/user_mailer create app/views/layouts/mailer.text.erb create app/views/layouts/mailer.html.erb invoke test_unit create test/mailers/user_mailer_test.rb create test/mailers/previews/user_mailer_preview.rb
# app/mailers/application_mailer.rb class ApplicationMailer < ActionMailer::Base default from: "from@example.com" layout 'mailer' end # app/mailers/user_mailer.rb class UserMailer < ApplicationMailer end
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
Edit the Mailer¶ ↑
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 < ApplicationMailer end
Let's add a method called welcome_email
, that will send an
email to the user's registered email address:
class UserMailer < ApplicationMailer 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 Mailer View¶ ↑
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.
Calling the Mailer¶ ↑
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:
$ bin/rails generate scaffold user name email login $ bin/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.
Action Mailer is nicely integrated with Active Job so you can send emails outside of the request-response cycle, so the user doesn't have to wait on it:
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_later 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
NOTE: Active Job's default behavior is to execute jobs
':inline'. So, you can use deliver_later
now to send
emails, and when you later decide to start sending them from a background
job, you'll only need to set up Active Job to use a queueing backend
(Sidekiq, Resque, etc).
If you want to send emails right away (from a cronjob for example) just
call deliver_now
:
class SendWeeklySummary def run User.find_each do |user| UserMailer.weekly_summary(user).deliver_now end end end
The method welcome_email
returns a
ActionMailer::MessageDelivery
object which can then just be
told deliver_now
or deliver_later
to send itself
out. The ActionMailer::MessageDelivery
object is just a
wrapper around a Mail::Message
. If you want to inspect, alter
or do anything else with the Mail::Message
object you can
access it with the message
method on the
ActionMailer::MessageDelivery
object.
Auto encoding header values¶ ↑
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.
Complete List of Action Mailer Methods¶ ↑
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 callheaders[: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.
Adding Attachments¶ ↑
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.
Making Inline Attachments¶ ↑
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, callingurl
on it and then passing the result into theimage_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' %>
Sending Email To Multiple Recipients¶ ↑
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.
Sending Email With Name¶ ↑
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¶ ↑
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 < ApplicationMailer 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 < ApplicationMailer 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.
Action Mailer Layouts¶ ↑
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 < ApplicationMailer 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 formats:
class UserMailer < ApplicationMailer 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.
Generating URLs in Action Mailer Views¶ ↑
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' }
Because of this behavior you cannot use any of the *_path
helpers inside of an email. Instead you will need to use the associated
*_url
helper. For example instead of using
<%= link_to 'welcome', welcome_path %>
You will need to use:
<%= link_to 'welcome', welcome_url %>
By using the full URL, your links will now work in your emails.
generating URLs with 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
.
generating URLs with named routes¶ ↑
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') %>
NOTE: non-GET
links require jQuery UJS and won't
work in mailer templates. They will result in normal GET
requests.
Sending Multipart Emails¶ ↑
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.
Sending Emails with Dynamic Delivery Options¶ ↑
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 < ApplicationMailer 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
Sending Emails without Template Rendering¶ ↑
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 < ApplicationMailer def welcome_email(user, email_body) mail(to: user.email, body: email_body, content_type: "text/html", subject: "Already rendered!") end end
Receiving Emails¶ ↑
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 < ApplicationMailer 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 Callbacks¶ ↑
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 abefore_action
but using instance variables set in your mailer action.
class UserMailer < ApplicationMailer 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.
Using Action Mailer Helpers¶ ↑
Action Mailer now just inherits from AbstractController
, so
you have access to the same generic helpers as you do in Action Controller.
Action Mailer Configuration¶ ↑
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
(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)</li><li>:enable_starttls_auto
-
Detects if STARTTLS is enabled in your SMTP server and starts to use it.
Defaults to
true
.</li><li>: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
, …).</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:<ul><li>:smtp
(default), can be configured by
using
config.action_mailer.smtp_settings
.</li><li>:sendmail
,
can be configured by using
config.action_mailer.sendmail_settings
.</li><li>:file
:
save emails to files; can be configured by using
config.action_mailer.file_settings
.</li><li>:test
:
save emails to ActionMailer::Base.deliveries
array.</li></ul>See API
docs for more info.| |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 Configuring Action Mailer in our Configuring Rails Applications guide.
Example Action Mailer Configuration¶ ↑
An example would be adding the following to your appropriate
config/environments/$RAILS_ENV.rb
file:
config.action_mailer.delivery_method = :sendmail # Defaults to: # config.action_mailer.sendmail_settings = { # location: '/usr/sbin/sendmail', # arguments: '-i -t' # } config.action_mailer.perform_deliveries = true config.action_mailer.raise_delivery_errors = true config.action_mailer.default_options = {from: 'no-reply@example.com'}
Action Mailer Configuration for Gmail¶ ↑
As Action Mailer now uses the Mail
gem, this becomes as simple as adding to your
config/environments/$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 }
Mailer Testing¶ ↑
You can find detailed instructions on how to test your mailers in the testing guide.
Intercepting Emails¶ ↑
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
if Rails.env.staging? ActionMailer::Base.register_interceptor(SandboxEmailInterceptor) end
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.