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: 'no-reply@example.com',
return_path: 'system@example.com'
def welcome(recipient)
@account = recipient
mail(to: recipient.email_address_with_name,
bcc: ["bcc@example.com", "Order Watcher <watcher@example.com>"])
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, while most fields likeTo:
From:
can only appear once in an email header, other fields likeX-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 asheaders({'X-No-Spam' => 'True', 'In-Reply-To' => '1234@message.id'})
-
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: 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 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 <%= @account.name %>,
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: "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" }
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.html.erb
-
signup_notification.xml.builder
-
signup_notification.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
.
Attachments
Sending attachment in emails is easy:
class ApplicationMailer < ActionMailer::Base
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 ApplicationMailer < ActionMailer::Base
def welcome(recipient)
attachments['free_book.pdf'] = File.read('path/to/file.pdf')
mail(to: recipient, subject: "New account information", body: "")
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 ApplicationMailer < ActionMailer::Base
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 Notifier < ActionMailer::Base
default sender: 'system@example.com'
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 Notifier < ActionMailer::Base
default 'Content-Transfer-Encoding' => '7bit',
content_description: 'This is a description'
end
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' => Proc.new { my_method }
private
def my_method
'some complex call'
end
end
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: "no-reply@example.org" }
Callbacks
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
mail
end
private
def add_inline_attachment!
attachments.inline["footer.jpg"] = File.read('/path/to/filename.jpg')
end
end
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.
Previewing emails
You can preview your email templates visually by adding a mailer preview
file to the ActionMailer::Base.preview_path
. Since most emails
do something interesting with database data, you'll need to write some
scenarios to load messages with fake data:
class NotifierPreview < ActionMailer::Preview
def welcome
Notifier.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
. The location of the mailer previews directory can be
configured using the preview_path
option which has a default
of test/mailers/previews
:
config.action_mailer.preview_path = "#{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 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 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 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 withdelivery_method :test
. Most useful for unit and functional testing.
- A
- D
- H
- M
- N
- R
- S
- ActionMailer::DeliveryMethods
- ActionMailer::Previews
- AbstractController::Rendering
- AbstractController::Helpers
- AbstractController::Translation
- AbstractController::Callbacks
- ActionView::Layouts
PROTECTED_IVARS | = | AbstractController::Rendering::DEFAULT_PROTECTED_INSTANCE_VARIABLES + [:@_action_has_layout] |
[W] | controller_path | Allows to set the name of current mailer. |
[W] | mailer_name | Allows to set the name of current mailer. |
Instantiate a new mailer object. If method_name
is not
nil
, the mailer will be initialized according to the named
method. If not, the mailer will remain uninitialized (useful when you only
need to invoke the “receive” method, for instance).
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 set the Content-Type, Content-Disposition, Content-Transfer-Encoding and base64 encode the contents of the attachment all for you.
You can also specify overrides if you want by passing a hash instead of a string:
mail.attachments['filename.jpg'] = {mime_type: 'application/x-gzip',
content: File.read('/path/to/filename.jpg')}
If you want to use a different encoding than Base64, you can pass an encoding in, but then it is up to you to pass in the content pre-encoded, and don't expect Mail to know how to decode this data:
file_content = SpecialEncode(File.read('/path/to/filename.jpg'))
mail.attachments['filename.jpg'] = {mime_type: 'application/x-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)
Sets the defaults through app configuration:
config.action_mailer.default { from: "no-reply@example.org" }
Aliased by ::default_options=
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
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.
Both methods accept 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 the Reply-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: 'no-reply@test.lindsaar.net',
bcc: 'email_logger@test.lindsaar.net',
reply_to: 'bounces@test.lindsaar.net'
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: 'no-reply@test.lindsaar.net'
def welcome
mail(to: 'mikel@test.lindsaar.net')
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: 'mikel@test.lindsaar.net') do |format|
format.text
format.html
end
You can even render plain text directly without using a template:
mail(to: 'mikel@test.lindsaar.net') 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: 'mikel@test.lindsaar.net') do |format|
format.text(content_transfer_encoding: "base64")
format.html
end
# File actionmailer/lib/action_mailer/base.rb, line 759 def mail(headers = {}, &block) return @_message if @_mail_was_called && headers.blank? && !block m = @_message # At the beginning, do not consider class default for content_type content_type = headers[:content_type] # Call all the procs (if any) default_values = {} self.class.default.each do |k,v| default_values[k] = v.is_a?(Proc) ? instance_eval(&v) : v end # Handle defaults headers = headers.reverse_merge(default_values) headers[:subject] ||= default_i18n_subject # Apply charset at the beginning so all fields are properly quoted m.charset = charset = headers[:charset] # Set configure delivery behavior wrap_delivery_behavior!(headers.delete(:delivery_method), headers.delete(:delivery_method_options)) # Assign all headers except parts_order, content_type and body assignable = headers.except(:parts_order, :content_type, :body, :template_name, :template_path) assignable.each { |k, v| m[k] = v } # Render the templates and blocks responses = collect_responses(headers, &block) @_mail_was_called = true create_parts_from_responses(m, responses) # Setup content type, reapply charset and handle parts order m.content_type = set_content_type(m, content_type, headers[:content_type]) m.charset = charset if m.multipart? m.body.set_sort_order(headers[:parts_order]) m.body.sort_parts! end m end
Returns the name of 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.
Receives a raw email, parses it into an email object, decodes it,
instantiates a new mailer, and passes the email object to the mailer
object's receive
method.
If you want your mailer to be able to process incoming messages, you'll
need to implement a receive
method that accepts the raw email
string as a parameter:
class MyMailer < ActionMailer::Base
def receive(mail)
# ...
end
end
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 one or more Interceptors which will be called before mail is sent.
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 one or more Observers which will be notified when mail is delivered.
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.
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 816 def set_content_type(m, user_content_type, class_default) params = m.content_type_parameters || {} case when user_content_type.present? user_content_type when m.has_attachments? if m.attachments.detect { |a| a.inline? } ["multipart", "related", params] else ["multipart", "mixed", params] end when m.multipart? ["multipart", "alternative", params] else m.content_type || class_default end end