Testable, composable, and adapter based Elixir email library for devs that love piping.

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Latest release:

2.3.0 - This version is safe to use because it has no known security vulnerabilities at this time. Find out if your coding project uses this component and get notified of any reported security vulnerabilities with Meterian-X Open Source Security Platform


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MIT   -   MIT License

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Not proprietary

OSI Compliant


Bamboo Circle CI Coverage Status

This README follows master, which may not be the currently published version! Use the docs for the published version of Bamboo.

Bamboo is part of the thoughtbot Elixir family of projects.

Flexible and easy to use email for Elixir.

  • Built-in support for popular mail delivery services. Bamboo ships with adapters for several popular mail delivery services, including Mandrill, Mailgun, and SendGrid. It's also quite easy to write your own delivery adapter if your platform isn't yet supported.
  • Deliver emails in the background. Most of the time you don't want or need to wait for the email to send. Bamboo makes it easy with Mailer.deliver_later.
  • A functional approach to mail delivery. Emails are created, manipulated, and sent using plain functions. This makes composition a breeze and fits naturally into your existing Elixir app.
  • Unit test with ease. Bamboo separates email creation and email delivery allowing you to test by asserting against email fields without the need for special functions.
  • Dead-simple integration tests. Bamboo provides helper functions to make integration testing easy and robust.
  • View sent emails during development. Bamboo provides a plug you can use in your router to view sent emails.
  • Integrate with Phoenix out of the box. Use Phoenix views and layouts to make rendering email easy.

See the docs for the most up to date information.

We designed Bamboo to be simple and powerful. If you run into anything that is less than exceptional, or you just need some help, please open an issue.


To install Bamboo, add it to your list of dependencies in mix.exs.

def deps do
  [{:bamboo, "~> 2.3.0"}]

You may also use the latest code available from master instead of a published version in hex:

def deps do
  [{:bamboo, github: "thoughtbot/bamboo"}]

Once you've added Bamboo to your list, update your dependencies by running:

$ mix deps.get

If you are using Elixir < 1.4, also ensure Bamboo is started alongside your application:

def application do
  [applications: [:bamboo]]

Getting Started

Bamboo separates the tasks of email creation and email sending. To use Bamboo, you'll need to define one or more email modules (email creation), define a mailer module (email sending), and provide some configuration.

To create emails, define an email module within your application.

# some/path/within/your/app/email.ex
defmodule MyApp.Email do
  import Bamboo.Email

  def welcome_email do
      to: "",
      from: "",
      subject: "Welcome to the app.",
      html_body: "<strong>Thanks for joining!</strong>",
      text_body: "Thanks for joining!"

In addition to the keyword syntax above you can also compose emails using pipes.

To send emails, define a mailer module for your application that uses Bamboo's mailer.

# some/path/within/your/app/mailer.ex
defmodule MyApp.Mailer do
  use Bamboo.Mailer, otp_app: :my_app

Your configuration will need to know your OTP application, your mailer module, the adapter you are using, and any additional configuration required by the adapter itself.

# config/config.exs
config :my_app, MyApp.Mailer,
  adapter: Bamboo.MandrillAdapter,
  api_key: "my_api_key"

Bamboo uses Hackney for making requests. If you want to pass options to Hackney directly, such as controlling timeouts, you can use the hackney_opts key:

# config/config.exs
config :my_app, MyApp.Mailer,
  adapter: Bamboo.MandrillAdapter,
  api_key: "my_api_key",
  hackney_opts: [
    recv_timeout: :timer.minutes(1),
    connect_timeout: :timer.minutes(1)

Other adapter-specific configuration may be required. Be sure to check the adapter's docs.

Now that you have configured Bamboo and defined your modules, you can deliver email in fitting places within your application.

defmodule MyApp.SomeControllerPerhaps do
  def send_welcome_email do
    Email.welcome_email()   # Create your email
    |> Mailer.deliver_now!() # Send your email

Your application is now set up to send email with Bamboo! 🎉

Using Adapters

An adapter is a set of instructions for how to communicate with a specific email delivery service. Bamboo ships with support for several popular services, there are others made available by the community, or you can use other services by writing a custom adapter.

To use an adapter, declare it in the configuration for your mailer:

# config/config.exs
config :my_app, MyApp.Mailer,
  adapter: Bamboo.MandrillAdapter

Bamboo provides adapters for use in development and testing. To use these adapters, declare them in the environment configuration.

The local adapter stores emails in memory that can be viewed during development. Declare its use in your dev environment.

# config/dev.exs
config :my_app, MyApp.Mailer,
  adapter: Bamboo.LocalAdapter

The test adapter sends emails to your running process allowing you to test mail delivery without emails being sent externally. Declare its use in your test environment.

# config/test.exs
config :my_app, MyApp.Mailer,
  adapter: Bamboo.TestAdapter

You can create new adapters for any environment by implementing the Bamboo.Adapter behaviour.

Delivering Emails in the Background

Often times you don't want to send an email right away because it can block process completion (e.g. a web request in Phoenix). Bamboo provides a deliver_later function on your mailers to send emails in the background. It also provides a Bamboo.DeliverLaterStrategy behaviour that you can implement to tailor your background email sending.

By default, deliver_later uses Bamboo.TaskSupervisorStrategy. This strategy sends the email right away, but it does so in the background without linking to the calling process, so errors in the mailer won't bring down your app.

You can also create custom strategies by implementing the Bamboo.DeliverLaterStrategy behaviour. For example, you could create strategies for adding emails to a background processing queue such as exq or toniq.

Composing with Pipes

In addition to creating emails with keyword lists you, can use pipe syntax to compose emails. This is particularly useful for providing defaults (e.g. from address, default layout, etc.)

defmodule MyApp.Email do
  import Bamboo.Email
  import Bamboo.Phoenix

  def welcome_email do
    base_email() # Build your default email then customize for welcome
    |> to("")
    |> subject("Welcome!!!")
    |> put_header("Reply-To", "")
    |> html_body("<strong>Welcome</strong>")
    |> text_body("Welcome")

  defp base_email do
    |> from("") # Set a default from
    |> put_html_layout({MyApp.LayoutView, "email.html"}) # Set default layout
    |> put_text_layout({MyApp.LayoutView, "email.text"}) # Set default text layout

Handling Recipients

The from, to, cc, and bcc addresses can be a string or a 2 element tuple. What happens if you try to send to a list of MyApp.Users? Transforming your data structure each time you send an email would be a pain.

# This stinks. Do you want to do this every time you create a new email?
users = for user <- users do

new_email(to: users)

Bamboo alleviates this pain by providing the Bamboo.Formatter protocol. By implementing the protocol for your data structure once, you can pass that struct directly to Bamboo anywhere it expects an address. See the Bamboo.Email and Bamboo.Formatter docs for more information and examples.


It's possible to configure per Mailer interceptors. Interceptors allow you to modify or block emails on the fly.

# config/config.exs
config :my_app, MyApp.Mailer,
  adapter: Bamboo.MandrillAdapter,
  interceptors: [MyApp.DenyListInterceptor]

An interceptor must implement the Bamboo.Interceptor behaviour. To prevent email being sent, you can block it with Bamboo.Email.block/1.

# some/path/within/your/app/deny_list_interceptor.ex
defmodule MyApp.DenyListInterceptor do
  @behaviour Bamboo.Interceptor
  @deny_list [""]

  def call(email) do
    if in @deny_list do

Using Phoenix Views and Layouts

Phoenix is not required to use Bamboo. But if you want to use Phoenix's views and layouts to render emails, see bamboo_phoenix and Bamboo.Phoenix.

Viewing Sent Emails

Bamboo comes with a handy plug for viewing emails sent in development. Now you don't have to look at the logs to get password resets, confirmation links, etc. Just open up the sent email viewer and click the link.

See Bamboo.SentEmailViewerPlug.

Here is what it looks like:

Screenshot of BambooSentEmailViewer

Mandrill Specific Functionality (tags, merge vars, templates, etc.)

Mandrill offers extra features on top of regular SMTP email like tagging, merge vars, templates, and scheduling emails to send in the future. See Bamboo.MandrillHelper.

SendGrid Specific Functionality (templates, substitution tags, scheduled delivery, etc.)

SendGrid offers extra features on top of regular SMTP email like transactional templates with substitution tags. See Bamboo.SendGridHelper.

JSON support

Bamboo comes with JSON support out of the box via the Jason library. To use it, add :jason to your dependencies:

{:jason, "~> 1.0"}

You can customize it to use another library via the :json_library configuration:

config :bamboo, :json_library, SomeOtherLib


Bamboo separates email creation and email sending. Test email creation by asserting against the email struct created by your functions. For example, assuming your welcome email accepts a user recipient, provides the correct from address, and provides specific text, you might test like this:

defmodule MyApp.EmailTest do
  use ExUnit.Case

  test "welcome email" do
    user = {"Ralph", ""}

    email = MyApp.Email.welcome_email(user)

    assert == user
    assert email.from == ""
    assert email.html_body =~ "<p>Thanks for joining</p>"
    assert email.text_body =~ "Thanks for joining"

Test email sending in integration tests by using the Bamboo.TestAdapter along with Bamboo.Test. For example, assuming during the registration process of your app an email is sent to the user welcoming them to the application, you might test this feature like this:

defmodule MyApp.RegistrationTest do
  use ExUnit.Case
  use Bamboo.Test

  # Remember to use the `Bamboo.TestAdapter` in your test config

  test "after registering, the user gets a welcome email" do
    user = new_user()
    expected_email = MyApp.Email.welcome_email(


    assert_delivered_email expected_email

  defp new_user do
    # Build a user appropriate to your application

See the documentation for Bamboo.Test for more examples and additional helper functions.

Available Adapters

Here is a list of adapters that either ship with Bamboo or have been made available by the community. Feel free to open an issue or a PR if you'd like to add a new adapter to the list.


Before opening a pull request, please open an issue first.

Once we've decided how to move forward with a pull request:

$ git clone
$ cd bamboo
$ mix deps.get
$ mix test
$ mix format

Once you've made your additions and mix test passes, go ahead and open a PR!

We run the test suite as well as formatter checks on CI. Make sure you are using the Elixir version defined in the .tool-versions file to have consistent formatting with what's being run on CI.

About thoughtbot


Bamboo is maintained and funded by thoughtbot, inc. The names and logos for thoughtbot are trademarks of thoughtbot, inc.

We love open-source software, Elixir, and Phoenix. See our other Elixir projects, or hire our Elixir Phoenix development team to design, develop, and grow your product.


Thanks to @mtwilliams for an early version of the SendGridAdapter.