Action Mailer Base
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.
$ bin/rails generate mailer Notifier
The generated model inherits from ApplicationMailer
which in turn inherits from ActionMailer::Base
. A mailer model defines methods used to generate an email message. In these methods, you can set up variables to be used in the mailer views, options on the mail itself such as the :from
address, and attachments.
class ApplicationMailer < ActionMailer::Base
default from: '[email protected]'
layout 'mailer'
end
class NotifierMailer < ApplicationMailer
default from: '[email protected]',
return_path: '[email protected]'
def welcome(recipient)
@account = recipient
mail(to: recipient.email_address_with_name,
bcc: ["[email protected]", "Order Watcher <[email protected]>"])
end
end
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['filename.png'] = File.read('path/to/filename.png')
-
attachments.inline[]=
- Allows you to add an inline attachment to your email in the same manner asattachments[]=
-
headers[]=
- Allows you to specify any header field in your email such asheaders['X-No-Spam'] = 'True'
. Note that declaring a header multiple times will add many fields of the same name. Readheaders
doc for more information. -
headers(hash)
- Allows you to specify multiple headers in your email such asheaders({'X-No-Spam' => 'True', 'In-Reply-To' => '[email protected]'})
-
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.html.erb
view file in a multipart/alternative
email.
If you want to explicitly render only certain templates, pass a block:
mail(to: user.email) do |format|
format.text
format.html
end
The block syntax is also useful in providing information specific to a part:
mail(to: user.email) do |format|
format.text(content_transfer_encoding: "base64")
format.html
end
Or even to render a special view:
mail(to: user.email) do |format|
format.text
format.html { render "some_other_template" }
end
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 mailer, 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_mailer/welcome.text.erb
would be used to generate the email.
Variables defined in the methods of your mailer model are accessible as instance variables in their corresponding view.
Emails by default are sent in plain text, so a sample view for our model example might look like this:
Hi <%= @account.name %>,
Thanks for joining our service! Please check back often.
You can even use Action View 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: "example.com", controller: "welcome", action: "greeting") %>
When using named routes you only need to supply the :host
:
<%= users_url(host: "example.com") %>
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: "example.com" }
You can also define a default_url_options
method on individual mailers to override these default settings per-mailer.
By default when config.force_ssl
is true
, URLs generated for hosts will use the HTTPS protocol.
Sending mail
Once a mailer action and template are defined, you can deliver your message or defer its creation and delivery for later:
NotifierMailer.welcome(User.first).deliver_now # sends the email
mail = NotifierMailer.welcome(User.first) # => an ActionMailer::MessageDelivery object
mail.deliver_now # generates and sends the email now
The ActionMailer::MessageDelivery
class is a wrapper around a delegate that will call your method to generate the mail. If you want direct access to the delegator, or Mail::Message
, you can call the message
method on the ActionMailer::MessageDelivery
object.
NotifierMailer.welcome(User.first).message # => a Mail::Message object
Action Mailer is nicely integrated with Active Job so you can generate and send emails in the background (example: outside of the request-response cycle, so the user doesn’t have to wait on it):
NotifierMailer.welcome(User.first).deliver_later # enqueue the email sending to Active Job
Note that deliver_later
will execute your method from the background job.
You never instantiate your mailer class. Rather, you just call the method you defined on the class itself. All instance methods are expected to return a message object to be sent.
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 to the message, as a separate part.
For example, if the following templates exist:
-
signup_notification.text.erb
-
signup_notification.html.erb
-
signup_notification.xml.builder
-
signup_notification.yml.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
.
Attachments
Sending attachment in emails is easy:
class NotifierMailer < ApplicationMailer
def welcome(recipient)
attachments['free_book.pdf'] = File.read('path/to/file.pdf')
mail(to: recipient, subject: "New account information")
end
end
Which will (if it had both a welcome.text.erb
and welcome.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 NotifierMailer < ApplicationMailer
def welcome(recipient)
attachments['free_book.pdf'] = File.read('path/to/file.pdf')
mail(to: recipient, subject: "New account information", body: "")
end
end
You can also send attachments with HTML template, in this case you need to add body, attachments, and custom content type like this:
class NotifierMailer < ApplicationMailer
def welcome(recipient)
attachments["free_book.pdf"] = File.read("path/to/file.pdf")
mail(to: recipient,
subject: "New account information",
content_type: "text/html",
body: "<html><body>Hello there</body></html>")
end
end
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 NotifierMailer < ApplicationMailer
def welcome(recipient)
attachments.inline['photo.png'] = File.read('path/to/photo.png')
mail(to: recipient, subject: "Here is what we look like")
end
end
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 NotifierMailer < ApplicationMailer
default sender: '[email protected]'
end
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 NotifierMailer < ApplicationMailer
default 'Content-Transfer-Encoding' => '7bit',
content_description: 'This is a description'
end
Finally, Action Mailer also supports passing Proc
and Lambda
objects into the default hash, so you can define methods that evaluate as the message is being generated:
class NotifierMailer < ApplicationMailer
default 'X-Special-Header' => Proc.new { my_method }, to: -> { @inviter.email_address }
private
def my_method
'some complex call'
end
end
Note that the proc/lambda is evaluated right at the start of the mail message generation, so if you set something in the default hash using a proc, and then set the same thing inside of your mailer method, it will get overwritten 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: "[email protected]" }
Callbacks
You can specify callbacks using before_action
and after_action
for configuring your messages, and using before_deliver
and after_deliver
for wrapping the delivery process. For example, when you want to add default inline attachments and log delivery for all messages sent out by a certain mailer class:
class NotifierMailer < ApplicationMailer
before_action :add_inline_attachment!
after_deliver :log_delivery
def welcome
mail
end
private
def add_inline_attachment!
attachments.inline["footer.jpg"] = File.read('/path/to/filename.jpg')
end
def log_delivery
Rails.logger.info "Sent email with message id '#{message.message_id}' at #{Time.current}."
end
end
Action callbacks in Action Mailer 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 Action Mailer classes so that headers are parsed properly.
Rescuing Errors
rescue
blocks inside of a mailer method cannot rescue errors that occur outside of rendering – for example, record deserialization errors in a background job, or errors from a third-party mail delivery service.
To rescue errors that occur during any part of the mailing process, use rescue_from:
class NotifierMailer < ApplicationMailer
rescue_from ActiveJob::DeserializationError do
# ...
end
rescue_from "SomeThirdPartyService::ApiError" do
# ...
end
def notify(recipient)
mail(to: recipient, subject: "Notification")
end
end
Previewing emails
You can preview your email templates visually by adding a mailer preview file to the ActionMailer::Base.preview_paths
. Since most emails do something interesting with database data, you’ll need to write some scenarios to load messages with fake data:
class NotifierMailerPreview < ActionMailer::Preview
def welcome
NotifierMailer.welcome(User.first)
end
end
Methods must return a Mail::Message
object which can be generated by calling the mailer method without the additional deliver_now
/ deliver_later
. The location of the mailer preview directories can be configured using the preview_paths
option which has a default of test/mailers/previews
:
config.action_mailer.preview_paths << "#{Rails.root}/lib/mailer_previews"
An overview of all previews is accessible at http://localhost:3000/rails/mailers
on a running development server instance.
Previews
can also be intercepted in a similar manner as deliveries can be by registering a preview interceptor that has a previewing_email
method:
class CssInlineStyler
def self.previewing_email(message)
# inline CSS styles
end
end
config.action_mailer.preview_interceptors :css_inline_styler
Note that interceptors need to be registered both with register_interceptor
and register_preview_interceptor
if they should operate on both sending and previewing emails.
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 tonil
for no logging. Compatible with both Ruby’s ownLogger
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 Base64 encoded),:login
(will send the password Base64 encoded) or:cram_md5
(combines a Challenge/Response mechanism to exchange information and a cryptographic MessageDigest
5 algorithm to hash important information) -
:enable_starttls
- Use STARTTLS when connecting to your SMTP server and fail if unsupported. Defaults tofalse
. Requires at least version 2.7 of theMail
gem. -
:enable_starttls_auto
- Detects if STARTTLS is enabled in your SMTP server and starts to use it. Defaults totrue
. -
: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'
or'peer'
) or directly the constant (OpenSSL::SSL::VERIFY_NONE
orOpenSSL::SSL::VERIFY_PEER
). -
:ssl/:tls
Enables the SMTP connection to use SMTP/TLS (SMTPS: SMTP over direct TLS connection) -
:open_timeout
Number of seconds to wait while attempting to open a connection. -
:read_timeout
Number of seconds to wait until timing-out a read(2) call.
-
-
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%w[ -i ]
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 applicationtmp/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 theMail
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 email 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 withdelivery_method :test
. Most useful for unit and functional testing. -
delivery_job
- The job class used withdeliver_later
. Mailers can set this to use a custom delivery job. Defaults toActionMailer::MailDeliveryJob
. -
deliver_later_queue_name
- The queue name used bydeliver_later
with the defaultdelivery_job
. Mailers can set this to use a custom queue name.
- A
- C
- D
- E
- H
- M
- N
- R
- S
- U
- ActionMailer::Callbacks
- ActionMailer::DeliveryMethods
- ActionMailer::QueuedDelivery
- ActionMailer::Rescuable
- ActionMailer::Parameterized
- ActionMailer::Previews
- ActionMailer::FormBuilder
- AbstractController::Rendering
- AbstractController::Helpers
- AbstractController::Translation
- AbstractController::Callbacks
- AbstractController::Caching
- ActionView::Layouts
Constants
PROTECTED_IVARS | = | AbstractController::Rendering::DEFAULT_PROTECTED_INSTANCE_VARIABLES + [:@_action_has_layout] |
Attributes
[W] | mailer_name | Allows to set the name of current mailer. |
Class Public methods
default(value = nil) Link
Sets the defaults through app configuration:
config.action_mailer.default(from: "[email protected]")
Aliased by ::default_options=
default_options=(value = nil) Link
Allows to set defaults through app configuration:
config.action_mailer.default_options = { from: "[email protected]" }
email_address_with_name(address, name) Link
Returns an email in the format “Name <[email protected]>”.
If the name is a blank string, it returns just the address.
mailer_name() Link
Returns the name of the current mailer. This method is also being used as a path for a view lookup. If this is an anonymous mailer, this method will return anonymous
instead.
new() Link
register_interceptor(interceptor) Link
Register an Interceptor which will be called before mail is sent. Either a class, string, or symbol can be passed in as the Interceptor. If a string or symbol is passed in it will be camelized and constantized.
register_interceptors(*interceptors) Link
Register one or more Interceptors which will be called before mail is sent.
register_observer(observer) Link
Register an Observer which will be notified when mail is delivered. Either a class, string, or symbol can be passed in as the Observer. If a string or symbol is passed in it will be camelized and constantized.
register_observers(*observers) Link
Register one or more Observers which will be notified when mail is delivered.
supports_path?() Link
Emails do not support relative path links.
unregister_interceptor(interceptor) Link
Unregister a previously registered Interceptor. Either a class, string, or symbol can be passed in as the Interceptor. If a string or symbol is passed in it will be camelized and constantized.
unregister_interceptors(*interceptors) Link
Unregister one or more previously registered Interceptors.
unregister_observer(observer) Link
Unregister a previously registered Observer. Either a class, string, or symbol can be passed in as the Observer. If a string or symbol is passed in it will be camelized and constantized.
unregister_observers(*observers) Link
Unregister one or more previously registered Observers.
Instance Public methods
attachments() Link
Allows you to add attachments to an email, like so:
mail.attachments['filename.jpg'] = File.read('/path/to/filename.jpg')
If you do this, then Mail
will take the file name and work out the mime type. It will also set the Content-Type
, Content-Disposition
, and Content-Transfer-Encoding
, and encode the contents of the attachment in Base64.
You can also specify overrides if you want by passing a hash instead of a string:
mail.attachments['filename.jpg'] = {mime_type: 'application/gzip',
content: File.read('/path/to/filename.jpg')}
If you want to use encoding other than Base64 then you will need to pass encoding type along with the pre-encoded content as Mail
doesn’t know how to decode the data:
file_content = SpecialEncode(File.read('/path/to/filename.jpg'))
mail.attachments['filename.jpg'] = {mime_type: 'application/gzip',
encoding: 'SpecialEncoding',
content: file_content }
You can also search for specific attachments:
# By Filename
mail.attachments['filename.jpg'] # => Mail::Part object or nil
# or by index
mail.attachments[0] # => Mail::Part (first attachment)
email_address_with_name(address, name) Link
Returns an email in the format “Name <[email protected]>”.
If the name is a blank string, it returns just the address.
headers(args = nil) Link
Allows you to pass random and unusual headers to the new Mail::Message
object which will add them to itself.
headers['X-Special-Domain-Specific-Header'] = "SecretValue"
You can also pass a hash into headers of header field names and values, which will then be set on the Mail::Message
object:
headers 'X-Special-Domain-Specific-Header' => "SecretValue",
'In-Reply-To' => incoming.message_id
The resulting Mail::Message
will have the following in its header:
X-Special-Domain-Specific-Header: SecretValue
Note about replacing already defined headers:
-
subject
-
sender
-
from
-
to
-
cc
-
bcc
-
reply-to
-
orig-date
-
message-id
-
references
Fields can only appear once in email headers while other fields such as X-Anything
can appear multiple times.
If you want to replace any header which already exists, first set it to nil
in order to reset the value otherwise another field will be added for the same header.
mail(headers = {}, &block) Link
The main method that creates the message and renders the email templates. There are two ways to call this method, with a block, or without a block.
It accepts a headers hash. This hash allows you to specify the most used headers in an email message, these are:
-
:subject
- The subject of the message, if this is omitted, Action Mailer will ask the Rails I18n class for a translated:subject
in the scope of[mailer_scope, action_name]
or if this is missing, will translate the humanized version of theaction_name
-
:to
- Who the message is destined for, can be a string of addresses, or an array of addresses. -
:from
- Who the message is from -
:cc
- Who you would like to Carbon-Copy on this email, can be a string of addresses, or an array of addresses. -
:bcc
- Who you would like to Blind-Carbon-Copy on this email, can be a string of addresses, or an array of addresses. -
:reply_to
- Who to set theReply-To
header of the email to. -
:date
- The date to say the email was sent on.
You can set default values for any of the above headers (except :date
) by using the ::default
class method:
class Notifier < ActionMailer::Base
default from: '[email protected]',
bcc: '[email protected]',
reply_to: '[email protected]'
end
If you need other headers not listed above, you can either pass them in as part of the headers hash or use the headers['name'] = value
method.
When a :return_path
is specified as header, that value will be used as the ‘envelope from’ address for the Mail
message. Setting this is useful when you want delivery notifications sent to a different address than the one in :from
. Mail
will actually use the :return_path
in preference to the :sender
in preference to the :from
field for the ‘envelope from’ value.
If you do not pass a block to the mail
method, it will find all templates in the view paths using by default the mailer name and the method name that it is being called from, it will then create parts for each of these templates intelligently, making educated guesses on correct content type and sequence, and return a fully prepared Mail::Message
ready to call :deliver
on to send.
For example:
class Notifier < ActionMailer::Base
default from: '[email protected]'
def welcome
mail(to: '[email protected]')
end
end
Will look for all templates at “app/views/notifier” with name “welcome”. If no welcome template exists, it will raise an ActionView::MissingTemplate error.
However, those can be customized:
mail(template_path: 'notifications', template_name: 'another')
And now it will look for all templates at “app/views/notifications” with name “another”.
If you do pass a block, you can render specific templates of your choice:
mail(to: '[email protected]') do |format|
format.text
format.html
end
You can even render plain text directly without using a template:
mail(to: '[email protected]') do |format|
format.text { render plain: "Hello Mikel!" }
format.html { render html: "<h1>Hello Mikel!</h1>".html_safe }
end
Which will render a multipart/alternative
email with text/plain
and text/html
parts.
The block syntax also allows you to customize the part headers if desired:
mail(to: '[email protected]') do |format|
format.text(content_transfer_encoding: "base64")
format.html
end
# File actionmailer/lib/action_mailer/base.rb, line 869 def mail(headers = {}, &block) return message if @_mail_was_called && headers.blank? && !block # At the beginning, do not consider class default for content_type content_type = headers[:content_type] headers = apply_defaults(headers) # Apply charset at the beginning so all fields are properly quoted message.charset = charset = headers[:charset] # Set configure delivery behavior wrap_delivery_behavior!(headers[:delivery_method], headers[:delivery_method_options]) assign_headers_to_message(message, headers) # Render the templates and blocks responses = collect_responses(headers, &block) @_mail_was_called = true create_parts_from_responses(message, responses) wrap_inline_attachments(message) # Set up content type, reapply charset and handle parts order message.content_type = set_content_type(message, content_type, headers[:content_type]) message.charset = charset if message.multipart? message.body.set_sort_order(headers[:parts_order]) message.body.sort_parts! end message end
mailer_name() Link
Returns the name of the mailer object.
Instance Private methods
default_i18n_subject(interpolations = {}) Link
Translates the subject
using Rails I18n class under [mailer_scope, action_name]
scope. If it does not find a translation for the subject
under the specified scope it will default to a humanized version of the action_name
. If the subject has interpolations, you can pass them through the interpolations
parameter.
set_content_type(m, user_content_type, class_default) Link
Used by mail
to set the content type of the message.
It will use the given user_content_type
, or multipart if the mail message has any attachments. If the attachments are inline, the content type will be “multipart/related”, otherwise “multipart/mixed”.
If there is no content type passed in via headers, and there are no attachments, or the message is multipart, then the default content type is used.
# File actionmailer/lib/action_mailer/base.rb, line 914 def set_content_type(m, user_content_type, class_default) # :doc: params = m.content_type_parameters || {} case when user_content_type.present? user_content_type when m.has_attachments? if m.attachments.all?(&:inline?) ["multipart", "related", params] else ["multipart", "mixed", params] end when m.multipart? ["multipart", "alternative", params] else m.content_type || class_default end end