# Swoosh


Compose, deliver and test your emails easily in Elixir.

Swoosh comes with many adapters, including SendGrid, Mandrill, Mailgun, Postmark and SMTP.
See the full list of [adapters below](#adapters).

The complete documentation for Swoosh is [available online at HexDocs](

## Requirements

Elixir 1.13+ and Erlang OTP 24+

## Getting started

# In your config/config.exs file
config :sample, Sample.Mailer,
  adapter: Swoosh.Adapters.Sendgrid,
  api_key: "SG.x.x"

# In your application code
defmodule Sample.Mailer do
  use Swoosh.Mailer, otp_app: :sample

defmodule Sample.UserEmail do
  import Swoosh.Email

  def welcome(user) do
    |> to({,})
    |> from({"Dr B Banner", ""})
    |> subject("Hello, Avengers!")
    |> html_body("<h1>Hello #{}</h1>")
    |> text_body("Hello #{}\n")

# In an IEx session
email = Sample.UserEmail.welcome(%{name: "Tony Stark", email: ""})

# Or in a Phoenix controller
defmodule Sample.UserController do
  use Phoenix.Controller
  alias Sample.UserEmail
  alias Sample.Mailer

  def create(conn, params) do
    user = create_user!(params)

    UserEmail.welcome(user) |> Mailer.deliver()

See [`Swoosh.Mailer`]( for more
configuration options.

## Installation

- Add swoosh to your list of dependencies in `mix.exs`:

  def deps do
    [{:swoosh, "~> 1.16"}]

- (Optional-ish) Most adapters (non SMTP ones) use `Swoosh.ApiClient` to talk
  to the service provider. Swoosh comes with `Swoosh.ApiClient.Hackney` configured
  by default. If you want to use it, you just need to include
  [`Hackney`]( as a dependency of your app.

  Swoosh also accepts [`Finch`]( and [`Req`]( out-of-the-box.
  See `Swoosh.ApiClient.Finch` and `Swoosh.ApiClient.Req` for details.

  If you need to integrate with another HTTP client, it's easy to define a new
  API client. Follow the `Swoosh.ApiClient` behaviour and configure Swoosh to
  use it:

  config :swoosh, :api_client, MyApp.ApiClient

  But if you don't need `Swoosh.ApiClient`, you can disable it by setting the value
  to `false`:

  config :swoosh, :api_client, false

  This is the case when you are using `Swoosh.Adapters.Local`,
  `Swoosh.Adapters.Test` and adapters that are SMTP based, that don't require
  an API client.

- (Optional) If you are using `Swoosh.Adapters.SMTP`,
  `Swoosh.Adapters.Sendmail` or `Swoosh.Adapters.AmazonSES`, you also need to
  add [`gen_smtp`]( to your dependencies:

  def deps do
      {:swoosh, "~> 1.6"},
      {:gen_smtp, "~> 1.0"}

## Adapters

Swoosh supports the most popular transactional email providers out of the box
and also has an SMTP adapter. Below is the list of the adapters currently

| Provider     | Swoosh adapter                                                                                      | Remarks          |
| ------------ | --------------------------------------------------------------------------------------------------- | ---------------- |
| SMTP         | [Swoosh.Adapters.SMTP](                 |                  |
| Mua          | [Swoosh.Adapters.Mua](                   | SMTP alternative |
| SendGrid     | [Swoosh.Adapters.Sendgrid](         |                  |
| Brevo        | [Swoosh.Adapters.Brevo](               | Sendinblue       |
| Sendmail     | [Swoosh.Adapters.Sendmail](         |                  |
| Mandrill     | [Swoosh.Adapters.Mandrill](         |                  |
| Mailgun      | [Swoosh.Adapters.Mailgun](           |                  |
| Mailjet      | [Swoosh.Adapters.Mailjet](           |                  |
| MsGraph      | [Swoosh.Adapters.MsGraph](           |                  |
| Postmark     | [Swoosh.Adapters.Postmark](         |                  |
| SparkPost    | [Swoosh.Adapters.SparkPost](       |                  |
| Amazon SES   | [Swoosh.Adapters.AmazonSES](       |                  |
| Amazon SES   | [Swoosh.Adapters.ExAwsAmazonSES](     |                  |
| Dyn          | [Swoosh.Adapters.Dyn](                   |                  |
| Scaleway     | [Swoosh.Adapters.Scaleway](         |                  |
| SocketLabs   | [Swoosh.Adapters.SocketLabs](     |                  |
| Gmail        | [Swoosh.Adapters.Gmail](               |                  |
| MailPace     | [Swoosh.Adapters.MailPace](         | OhMySMTP         |
| SMTP2GO      | [Swoosh.Adapters.SMTP2GO](           |                  |
| ProtonBridge | [Swoosh.Adapters.ProtonBridge]( |                  |
| Mailtrap     | [Swoosh.Adapters.Mailtrap](         |                  |

Configure which adapter you want to use by updating your `config/config.exs`

config :sample, Sample.Mailer,
  adapter: Swoosh.Adapters.SMTP
  # adapter config (api keys, etc.)

Check the documentation of the adapter you want to use for more specific
configurations and instructions.

Adding new adapters is super easy and we are definitely looking for
contributions on that front. Get in touch if you want to help!

## Recipient

The Recipient Protocol enables you to easily make your structs compatible
with Swoosh functions.

defmodule MyUser do
  @derive {Swoosh.Email.Recipient, name: :name, address: :email}
  defstruct [:name, :email, :other_props]

Now you can directly pass `%MyUser{}` to `from`, `to`, `cc`, `bcc`, etc.
See `Swoosh.Email.Recipient` for more details.

## Async Emails

Swoosh does not make any special arrangements for sending emails in a
non-blocking manner. Opposite to some stacks, sending emails, talking
to third party apps, etc in Elixir do not block or interfere with other
requests, so you should resort to async emails only when necessary.

One simple way to deliver emails asynchronously is by leveraging Elixir's
standard library. First add a Task supervisor to your application root,
usually at `lib/my_app/application.ex`:

def start(_, _) do
  children = [
    # Before the endpoint
    {Task.Supervisor, name: MyApp.AsyncEmailSupervisor},

  Supervisor.start_link(children, strategy: :one_for_one)

Now, whenever you want to send an email:

Task.Supervisor.start_child(MyApp.AsyncEmailSupervisor, fn ->
  %{name: "Tony Stark", email: ""}
  |> Sample.UserEmail.welcome()
  |> Sample.Mailer.deliver()

Please take a look at the official docs for
[Task]( and
[Task.Supervisor]( for further

One of the downsides of sending email asynchronously is that failures won't
be reported to the user, who won't have an opportunity to try again immediately,
and tasks by default do not retry on errors. Therefore, if the email must be
delivered asynchronously, a safer solution would be to use a queue or job system.
Elixir's ecosystem has many
[job queue libraries](

- [Oban]( is the current community favourite.
  It uses PostgreSQL for storage and coordination.
- [Exq]( uses Redis and is compatible with
  Resque / Sidekiq.

## Attachments

You can attach files to your email using the `Swoosh.Email.attachment/2`
function. Just give the path of your file as an argument and we will do the
rest. It also works with a `%Plug.Upload{}` struct, or a `%Swoosh.Attachment{}`
struct, which can be constructed using `` detailed here in
the [docs](

All built-in adapters have support for attachments.

|> to("")
|> from({"Jarvis", ""})
|> subject("Invoice May")
|> text_body("Here is the invoice for your superhero services in May.")
|> attachment("/Users/jarvis/invoice-peter-may.pdf")

## Testing

In your `config/test.exs` file set your mailer's adapter to
`Swoosh.Adapters.Test` so that you can use the assertions provided by Swoosh in
`Swoosh.TestAssertions` module.

defmodule Sample.UserTest do
  use ExUnit.Case, async: true

  import Swoosh.TestAssertions

  test "send email on user signup" do
    # Assuming `create_user` creates a new user then sends out a
    # `Sample.UserEmail.welcome` email
    user = create_user(%{username: "ironman", email: ""})
    assert_email_sent Sample.UserEmail.welcome(user)

## Mailbox preview in the browser

Swoosh ships with a Plug that allows you to preview the emails in the local
(in-memory) mailbox. It's particularly convenient in development when you want
to check what your email will look like while testing the various flows of your

For email to reach this mailbox you will need to set your `Mailer` adapter to

# in config/dev.exs
config :sample, MyApp.Mailer,
  adapter: Swoosh.Adapters.Local

In your Phoenix project you can `forward` directly to the plug
without spinning up a separate webserver, like this:

# in web/router.ex
if Mix.env == :dev do
  scope "/dev" do
    pipe_through [:browser]

    forward "/mailbox", Plug.Swoosh.MailboxPreview

You can also start a new server if your application does not depends on Phoenix:

# in config/dev.exs
# to run the preview server alongside your app
# which may not have a web interface already
config :swoosh, serve_mailbox: true

# in config/dev.exs
# to change the preview server port (4000 by default)
config :swoosh, serve_mailbox: true, preview_port: 4001

When using `serve_mailbox: true` make sure to have either `plug_cowboy` or
`bandit` as a dependency of your app.

{:plug_cowboy, ">= 1.0.0"}
# or
{:bandit, ">= 1.0.0"}

And finally you can also use the following Mix task to start the mailbox
preview server independently:

mix swoosh.mailbox.server

_Note_: the mailbox preview won't display emails
being sent from outside its own node. So if you are testing using an `IEx` session,
it's recommended to boot the application in the same session.
`iex -S mix phx.server` or `iex -S mix swoosh.mailbox.server` will do the trick.

If you are curious, this is how it the mailbox preview looks like:


_Note_ : To show the preview we use the cdn-version of Tailwindcss. If you have set a `content-security-policy` you may have to add `` to `default-src` to have the correct make up.

The preview is also available as a JSON endpoint.

curl http://localhost:4000/dev/mailbox/json

### Production

Swoosh starts a memory storage process for local adapter by default. Normally
it does no harm being left around in production. However, if it is causing
problems, or you don't like having it around, it can be disabled like so:

# config/prod.exs
config :swoosh, local: false

## Telemetry

The following events are emitted:

- `[:swoosh, :deliver, :start]`: occurs when `Mailer.deliver/2` begins.
- `[:swoosh, :deliver, :stop]`: occurs when `Mailer.deliver/2` completes.
- `[:swoosh, :deliver, :exception]`: occurs when `Mailer.deliver/2` throws an exception.
- `[:swoosh, :deliver_many, :start]`: occurs when `Mailer.deliver_many/2` begins.
- `[:swoosh, :deliver_many, :stop]`: occurs when `Mailer.deliver_many/2` completes.
- `[:swoosh, :deliver_many, :exception]`: occurs when `Mailer.deliver_many/2`
  throws an exception.

View [example in docs](

## Documentation

Documentation is written into the library, you will find it in the source code,
accessible from `iex` and of course, it all gets published to

## Contributing

We are grateful for any contributions. Before you submit an issue or a pull
request, remember to:

- Look at our [Contributing guidelines](
- Not use the issue tracker for help or support requests (try StackOverflow,
  IRC or Slack instead)
- Do a quick search in the issue tracker to make sure the issues hasn't been
  reported yet.
- Look and follow the [Code of Conduct]( Be nice and have fun!

### Running tests

Clone the repo and fetch its dependencies:

git clone
cd swoosh
mix deps.get
mix test

### Building docs

MIX_ENV=docs mix docs